Identify the direct object in the sentence: "She wrote a letter."

In the sentence "She wrote a letter," the direct object is "a letter." A direct object is a noun or pronoun that receives the action of the verb. In this case, the verb "wrote" is an action performed by the subject "She." To determine the direct object, you can ask the question, "What did she write?" The answer is "a letter," which is what was written. This shows that "a letter" is the recipient of the action of the verb. Therefore, it correctly identifies the direct object in this sentence.