Read the passage. the panther paused to sniff the humid night air. it heard noises up ahead, but it did not recognize the sounds. the strange noises continued, and the panther became frightened. the panther crept into a cave because it was afraid. which sentence from the passage is complex? the panther paused to sniff the humid night air. it heard noises up ahead, but it did not recognize the sounds. the strange noises continued, and the panther became frightened. the panther crept into a cave because it was afraid.

D). The panther crept into a cave because it was afraid.

Explanation:

A complex sentence is illustrated as a sentence that consists of at least one dependent or subordinate clause beginning with subordinate conjunction along with a principal or independent clause where the former is dependent on the latter to accomplish its meaning.

As per the question, option D exemplifies a complex sentence as it comprises of an independent clause 'The panther crept into a cave' which functions to accomplish the meaning of subordinate clause 'because it was afraid' followed by it beginning with the subordinate conjunction 'because'. The other options either exemplify a simple sentence(option A) or a compound sentence(options B and C due to the lack of subordinate conjunction).