A.I. Explanation:

Correct answer: ought

Explanation: The word 'ought' is used to express a recommendation or obligation, fitting grammatically as it indicates what one should do to achieve happiness and safety. It aligns with the modal verb usage in the context of advice or suggestion.

Meaning: 'Ought' means 'should' or 'is expected to,' indicating a strong recommendation for having hobbies to be happy and safe.

Wrong options:

• will: 'Will' indicates future intention but does not convey obligation or recommendation, making it less suitable in this context.
• must: 'Must' implies a strong necessity, which is too forceful for the advice being given here.
• should: 'Should' is similar to 'ought' but is less formal; 'ought' is more appropriate in this context.

Correct answer: aggravates

Explanation: The word 'aggravates' fits well as it means to make a situation worse, which aligns with the context of increasing mental strain. It is grammatically correct as it matches the subject of the sentence and conveys the intended meaning.

Meaning: 'Aggravates' means to worsen or intensify a problem, indicating that starting late in life increases mental strain.

Wrong options:

• makes: 'Makes' is too vague and does not convey the negative impact implied in the sentence.
• initiate: 'Initiate' means to begin something, which does not fit the context of increasing strain.
• deteriorates: 'Deteriorates' implies a decline but does not specifically convey the idea of worsening strain as effectively as 'aggravates'.

Correct answer: acquire

Explanation: The word 'acquire' is appropriate as it means to gain or obtain knowledge, fitting grammatically and contextually with the idea of gaining knowledge unrelated to daily work.

Meaning: 'Acquire' means to gain or obtain something, in this case, knowledge of various topics.

Wrong options:

• lose: 'Lose' is the opposite of what is intended, as it implies a reduction in knowledge rather than gaining it.
• deny: 'Deny' does not fit contextually, as it suggests refusing something rather than gaining knowledge.
• move: 'Move' is unrelated to the context of gaining knowledge and does not fit grammatically.

Correct answer: Broadly

Explanation: The word 'Broadly' is suitable as it indicates a general perspective, fitting grammatically and contextually with the classification of human beings into three classes.

Meaning: 'Broadly' means in general terms or overall, suggesting a wide perspective on human classification.

Wrong options:

• Calmly: 'Calmly' refers to a manner of doing something and does not fit the context of categorization.
• Mainly: 'Mainly' suggests a focus on the primary aspect, which is too narrow for the general classification intended here.
• Only: 'Only' restricts the scope and does not convey the intended broad categorization of human beings.