Meaning: 'Abundance' means a large quantity or plenty of something, in this case, referring to the vast variety of marine life found in the reef.

Wrong options:

• access: Access refers to the ability to enter or use something, which does not fit the context of describing the quantity of marine life.
• acquaintance: Acquaintance refers to a person one knows slightly, which is unrelated to the context of marine life.
• equivalence: Equivalence means being equal in value or meaning, which does not apply to the context of describing the quantity of marine life.

Correct answer: picturesque

Explanation: The word 'picturesque' is an adjective that describes something visually attractive, especially in a way that is suitable for being painted or photographed. It fits contextually as it describes the tropical islands in a way that enhances the overall beauty of the Great Barrier Reef.

Meaning: 'Picturesque' means visually charming or quaint, often in a way that resembles a picture, which is fitting for the beautiful tropical islands mentioned.

Wrong options:

• illusionary: Illusionary refers to something that is deceptive or not real, which does not fit the context of describing actual islands.
• exterritorial: Exterritorial means outside the jurisdiction of a territory, which is irrelevant to the description of islands.
• visionary: Visionary refers to someone with original ideas about what the future could be like, which does not apply to the description of islands.

Correct answer: sought

Explanation: The word 'sought' is the past participle of 'seek' and is used here as an adjective to describe the tourist destinations that are highly desired or in demand. It fits grammatically and contextually, emphasizing the popularity of the Great Barrier Reef.

Meaning: 'Sought' means desired or wanted, indicating that the Great Barrier Reef is a highly desired destination for tourists.

Wrong options:

• thought: Thought is a noun referring to an idea or opinion, which does not fit grammatically or contextually in this context.
• caught: Caught is the past tense of catch, which does not apply to the context of describing tourist destinations.
• met: Met is the past tense of meet, which is unrelated to the context of describing the desirability of a destination.

Correct answer: experiences

Explanation: The word 'experiences' is a noun that refers to events or activities that a person has gone through. It fits grammatically and contextually, as it describes the various activities a visitor can enjoy at the Great Barrier Reef.

Meaning: 'Experiences' means events or activities that one participates in, highlighting the various enjoyable activities available to visitors.

Wrong options:

• expeditions: Expeditions refer to journeys undertaken for a specific purpose, which is too narrow a term compared to the broader range of activities described.
• expectations: Expectations are beliefs about what will happen in the future, which does not fit the context of describing activities.
• emporiums: Emporiums are large retail stores, which do not relate to the activities available at the Great Barrier Reef.