A.I. Explanation:

Correct answer: were revealed

Explanation: The phrase 'were revealed' is in the past passive voice, which is appropriate here as it indicates that the fossil plants were discovered and analyzed in the past, aligning with the historical context of the sentence.

Meaning: 'Were revealed' means that something was made known or disclosed in the past, specifically referring to the analysis of the fossil plants.

Wrong options:

• revealed: The word 'revealed' is in the active voice and does not fit the passive construction required here, as it implies an ongoing action rather than a completed one.
• have revealed: 'Have revealed' suggests a present perfect tense, which is inappropriate in this context since the discovery and analysis occurred in the past.
• are revealed: 'Are revealed' is in the present tense, which does not match the past context of the sentence.

Correct answer: must

Explanation: The word 'must' indicates a strong assumption or conclusion based on evidence, which fits the context of deducing the past climate of Antarctica from fossil evidence.

Meaning: 'Must' implies a high degree of certainty about something being true, in this case, that Antarctica was warmer in the past.

Wrong options:

• ought to: 'Ought to' suggests a recommendation or moral obligation, which does not fit the context of making a factual deduction about the past climate.
• can: The word 'can' indicates possibility but lacks the certainty required in this context, as the statement is based on evidence.
• should: 'Should' implies a suggestion or expectation, which is less definitive than 'must' and does not convey the same level of certainty.

Correct answer: support

Explanation: The word 'support' is used here to indicate that the similarity of the fossils provides backing or evidence for the idea, fitting grammatically and contextually.

Meaning: 'Support' means to provide evidence or assistance to an idea or argument, in this case, reinforcing the theory about Antarctica's geological history.

Wrong options:

• basis: 'Basis' refers to the underlying foundation of an idea, but does not fit grammatically as it would require a different structure in the sentence.
• foundations: Similar to 'basis', 'foundations' implies a base for an idea but does not work in this context as it lacks the active sense of providing evidence.
• ground: 'Ground' can refer to a basis for an argument but is less commonly used in this context and does not fit the grammatical structure.

Correct answer: bear

Explanation: The verb 'bear' is used here to indicate that the fossilized trees carry or exhibit a resemblance, which fits the context of comparison and is grammatically correct.

Meaning: 'Bear' means to carry or possess a certain quality, in this case, the resemblance to petrified forests.

Wrong options:

• provide: While 'provide' could fit in a different context, it does not convey the idea of resemblance as effectively as 'bear' does in this sentence.
• give: 'Give' is too vague in this context and does not specifically indicate the nature of the resemblance being discussed.
• fetch: 'Fetch' implies retrieving something and does not fit the context of describing a resemblance.

Correct answer: insights

Explanation: The word 'insights' refers to deep understandings or realizations, which is appropriate in the context of studying climate shifts and their implications.

Meaning: 'Insights' means clear or deep perceptions about a complex situation, in this case, related to global warming.

Wrong options:

• understandings: 'Understandings' is a more general term and does not convey the depth of perception that 'insights' does in this context.
• findings: 'Findings' refers to results from research but lacks the nuance of deeper comprehension implied by 'insights'.
• conclusions: 'Conclusions' suggests final judgments or decisions, which does not capture the ongoing process of gaining knowledge implied by 'insights'.