Answer: The right answer is the D) whether.
Explanation: Just to elaborate a little on the answer, it can also be added that homophone words (from the Greek homós, which means "the same," and phōnḗ, which means "sound" or "voice") are those that have the same sound when they are pronounced, but they have different meanings and are often spelt differently. Other examples are "see" and "sea," "here" and "hear," and "by," "bye," and "buy." Some words in English have four, five, and up to seven homophones.
