Choose the sentence where 'high' is used as an adverb :-

The correct answer is Option (2) → Some birds fly high in the sky.

An adverb is a word that tells how, when, where or how much something happens. It can also describe an adjective or another adverb, for example she sings sweetly, very hot.

"High" as adjective and adverb:

• An adjective describes a noun: high ambition, high hopes, or comes after "is": her confidence is high.
• An adverb describes a verb: it tells how / where the action happens.
• This sentence: "high" tells where the birds fly, so it describes the verb "fly" and is an adverb.

Why the Other Options are Incorrect?

Option 1: We must have high ambition. — Incorrect. "High" describes the noun "ambition", so it is an adjective.

Option 3: She had high hopes from his son. — Incorrect. "High" describes the noun "hopes", so it is an adjective.

Option 4: Her confidence is high. — Incorrect. "High" comes after the linking verb "is" and describes the noun "confidence", so it is an adjective.

Contrast: "high" before a noun or after "is" is an adjective (high hopes, is high). "High" after an action verb is an adverb (fly high).