Meaning: 'Unearthed' means to discover or bring to light something that was previously hidden or unknown.

Wrong options:

• analysing: 'Analysing' is a gerund that refers to the process of examining something in detail, which does not convey the action of revealing a discovery.
• discovers: 'Discovers' is a verb that implies finding something for the first time, but it does not fit the past tense structure required in this context.

Correct answer: intricate

Explanation: The term 'intricate' is an adjective that describes something that is complex and detailed, which is appropriate in the context of discussing the evolutionary history of parrots and falcons.

Meaning: 'Intricate' means having many complex and interrelated parts.

Wrong options:

• historian: 'Historian' is a noun that refers to a person who studies or writes about history, which does not fit as it does not describe the nature of the evolutionary history.
• closely: 'Closely' is an adverb that describes the manner of connection, but it does not describe the complexity of the evolutionary history.

Correct answer: closely

Explanation: The word 'closely' is an adverb that modifies the verb 'linked,' indicating the degree of connection between falcons and parrots, which fits the context of their phylogenetic relationships.

Meaning: 'Closely' means in a close manner, indicating a strong or intimate connection.

Wrong options:

• intricate: 'Intricate' is an adjective that describes complexity, but it does not fit as it does not describe the manner of the link.
• analysing: 'Analysing' is a gerund that does not relate to the degree of connection and does not fit grammatically.

Correct answer: persistent

Explanation: The term 'persistent' is an adjective that describes the ongoing nature of scientific inquiry, fitting well in the context of emphasizing the importance of continuous effort in research.

Meaning: 'Persistent' means continuing firmly or obstinately in a course of action despite difficulty or opposition.

Wrong options:

• sphere: 'Sphere' is a noun that refers to a domain or area, which does not fit as it does not describe the nature of scientific inquiry.
• historian: 'Historian' is a noun that does not relate to the concept of inquiry and does not fit grammatically.

Correct answer: sphere

Explanation: The word 'sphere' is a noun that refers to a domain or field of study, which fits the context of discussing the academic environment where knowledge is expanded.

Meaning: 'Sphere' refers to a particular area of activity or interest, especially in academic contexts.

Wrong options:

• persistent: 'Persistent' is an adjective that describes a quality of inquiry, but it does not fit as it does not refer to a domain or field.
• analysing: 'Analysing' is a gerund that refers to the action of examining, which does not fit as it does not describe a domain.