Choose the most suitable option to replace the highlighted part of the sentence: where is he hiding.

Explanation

In an embedded (indirect) question, the word order should be:
Question word + subject + verb
So, instead of "where is he hiding", it should be "where he is hiding."
Correct sentence:
"No one knows where he is hiding."
where is he hide – Incorrect grammar
where he is hiding at – Incorrect because "at" is unnecessary
where he is hiding – Correct
where he has hidden is – Incorrect sentence structure
Correct Answer: where he is hiding