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'.