A.I. Explanation:

Correct answer: received

Explanation: The word 'received' is the simple past tense of the verb, which is appropriate here as it indicates a completed action that took place in the past, aligning with the context of a recent graduation ceremony. The sentence structure requires a past tense verb to convey that the honorary degree was conferred at that specific event.

Meaning: 'Received' means to have been given or awarded something, in this case, an honorary degree.

Wrong options:

• was receiving: This option suggests an ongoing action in the past, which does not fit the context of a completed event.
• had received: This past perfect tense implies an action completed before another past action, which is unnecessary here since the graduation ceremony is the main event.
• is received: This present tense form does not fit as it suggests a current action rather than a past event.

Correct answer: played

Explanation: The verb 'played' fits grammatically as it is in the simple past tense, indicating a completed action that aligns with the context of Professor Couch's contributions to the discovery of the Universe's expansion. It also matches the subject 'Professor Couch' and the context of his role in a significant scientific finding.

Meaning: 'Played' means to have taken part in or contributed to something, indicating his involvement in the discovery.

Wrong options:

• found: This verb implies a discovery rather than a role in a process, which does not accurately describe his contribution in this context.
• done: This option is too vague and does not convey the specific nature of his involvement in the discovery.
• led: While this suggests leadership, it does not accurately reflect his role as a contributor rather than a leader in the discovery.

Correct answer: which

Explanation: The word 'which' is a relative pronoun that introduces a non-defining relative clause, providing additional information about 'galaxy clusters.' It correctly links the clause to the noun it describes, maintaining grammatical coherence and clarity in the sentence.

Meaning: 'Which' is used to introduce additional information about something previously mentioned, in this case, galaxy clusters.

Wrong options:

• those: This demonstrative pronoun does not fit grammatically as it would require a different sentence structure to refer back to 'galaxy clusters.'
• they: This pronoun is not appropriate here as it would require a different grammatical structure, and it does not introduce a clause.
• who: This relative pronoun is used for people, not objects or concepts, making it unsuitable for referring to 'galaxy clusters.'

Correct answer: In addition to

Explanation: The phrase 'In addition to' is a transitional phrase that indicates an additional point related to the previous statement. It fits grammatically and contextually as it introduces another aspect of Professor Couch's activities, maintaining the flow of information in the sentence.

Meaning: 'In addition to' means 'besides' or 'as well as,' indicating that there is more to consider regarding his activities.

Wrong options:

• As a result of: This phrase implies a consequence, which does not fit the context of adding information about his activities.
• Regarding: This word suggests a focus on a specific topic rather than adding information, making it unsuitable here.
• Instead of: This phrase indicates a substitution, which does not align with the intent of adding to the list of activities.