Solve this multiple-choice question and choose the correct option.

Astronomical instruments: What do large astronomical telescopes use as the objective? Consider modern observatory-class instruments designed for faint, distant objects. Choose the correct option.

Difficulty: Easy

Convex lens (large refractor)
Concave lens
Concave mirror (reflector)
Plane mirror

Correct Answer: Concave mirror (reflector)

Explanation:

ConceptReflecting telescopes use large concave mirrors: lighter for large apertures, no chromatic aberration, easier support from behind.

Final AnswerConcave mirror (reflector)

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