A.I. Explanation:

Correct answer: axis

Explanation: The word 'axis' is the correct term as it refers to the imaginary line around which the Earth rotates, fitting grammatically and contextually into the sentence about the planet's rotation.

Meaning: 'Axis' means the central line around which something rotates, specifically in this context, it refers to Earth's rotational axis.

Wrong options:

• sundial: 'Sundial' refers to a device that tells the time based on the position of the sun, which does not relate to the concept of rotation.
• core: 'Core' refers to the innermost part of the Earth, which is not relevant to the rotation of the planet.
• surface: 'Surface' refers to the outermost layer of the Earth, but it does not accurately describe the line around which the Earth rotates.

Correct answer: dictated

Explanation: The word 'dictated' fits well as it indicates that the time is controlled or determined by Coordinated Universal Time (UTC), aligning grammatically and contextually with the sentence.

Meaning: 'Dictated' means to control or determine something, in this case, how time is set based on UTC.

Wrong options:

• delegated: 'Delegated' means assigned to someone else, which does not fit the context of time being controlled by UTC.
• addicted: 'Addicted' refers to a dependency on something, which is not relevant to the concept of time regulation.
• rotated: 'Rotated' refers to turning around an axis, which does not convey the idea of time being set or controlled.

Correct answer: dependent

Explanation: The word 'dependent' is appropriate as it indicates that astronomical time relies on the duration of Earth's rotation, fitting both grammatically and contextually.

Meaning: 'Dependent' means relying on or being influenced by something, in this case, the time based on Earth's rotation.

Wrong options:

• focused: 'Focused' means concentrated on something, which does not accurately describe the relationship between time and Earth's rotation.
• born: 'Born' refers to being brought into existence, which is not relevant to the concept of time measurement.
• available: 'Available' means accessible or ready for use, which does not convey the idea of time being reliant on Earth's rotation.

Correct answer: who

Explanation: The word 'who' is the correct choice as it serves as a pronoun referring to people, fitting grammatically and contextually in the sentence about those observing Earth's rotation.

Meaning: 'Who' is a pronoun used to refer to people, in this case, those who watch the Earth's rotation.

Wrong options:

• when: 'When' is a conjunction or adverb indicating time, which does not fit as a subject in this context.
• whose: 'Whose' is a possessive pronoun, which does not correctly refer to the subject of the sentence.
• whom: 'Whom' is an object pronoun, which is not appropriate as the subject in this context.