Read the following paragraph about myths and then answer the question that follows. Ancient cultures created myths to explain events they did not understand. Myths usually answered perplexing questions. They helped people make sense of the world. Now, science should explain why the sun rises in the east and sets in the west. Prior to this discovery, it was a mystery.

Which sentence contains a grammar usage error?

A. Ancient cultures created myths to explain events they did not understand.

B. Myths usually answered perplexing questions.

C. They helped people make sense of the world.

D. Now, science should explain why the sun rises in the east and sets in the west.