1.With a cool, silent determination (that seemed to be instinctive), the kitten stalked and pounced on the ball of the yarn.

2.The fans were cheering (as though they had just won the national championship).
3.(As the sun set), a feeling of peace came over the campers.
4.racquetball is a fast, exciting game (that can be played by two, three, or four people).

I have to identify the clause in () as adj or adv clause.

1.adjective clause
2.adverb
3.adverb
4.adjective

All are correct.

To identify whether the clause in () is an adjective clause or an adverb clause, we need to determine the function of the clause in relation to the main clause.

1. "(that seemed to be instinctive)" in sentence 1: This clause is describing or modifying the noun "determination," so it is functioning as an adjective clause. Therefore, the answer is "adjective clause."

2. "(as though they had just won the national championship)" in sentence 2: This clause is describing or modifying the verb "cheering," indicating the reason or manner of the cheering. Therefore, it is functioning as an adverb clause. Therefore, the answer is "adverb."

3. "(As the sun set)" in sentence 3: This clause is describing or modifying the verb "came," indicating the time or condition under which the feeling of peace occurred. Therefore, it is functioning as an adverb clause. Therefore, the answer is "adverb."

4. "(that can be played by two, three, or four people)" in sentence 4: This clause is describing or modifying the noun "game," so it is functioning as an adjective clause. Therefore, the answer is "adjective clause."