Find the correct answer. Why weren't you answering your phone?

The question uses the past tense "weren't answering", implying an event that occurred in the past. Therefore, the answer should also be in the past tense to maintain grammatical consistency. The phrase "Because I was sleeping" correctly uses the past continuous tense, aligning with the past tense of the question. The other options are either in the present tense ("Because I sleep", "Because I am sleeping") or use an incorrect past participle form ("Because I was slept").