The answer is D. Explain.
Teach, instruct, and educate all involve imparting knowledge or skills to someone. Explain, on the other hand, means to make something clear or understandable.
Teach is the most general of these words. It can refer to any act of imparting knowledge or skills, whether formally or informally. Instruct is similar to teach, but it often implies a more structured or formal setting. Educate can also refer to a formal process of learning, but it can also mean to develop someone’s knowledge or understanding in a general sense. Explain is the only word on the list that does not involve imparting knowledge or skills. Instead, it means to make something clear or understandable.
For example, a teacher might teach a class about the history of the United States. An instructor might instruct a student on how to use a computer. A parent might educate their child about the dangers of drugs. And a friend might explain to you how to use a new app.
In this case, the word that is different from the rest is explain. Explain is the only word on the list that does not involve imparting knowledge or skills. Instead, it means to make something clear or understandable.