Introduction:
The correct answer to the question "Are you sleeping?" is "you sleeping." In this response, the subject "you" is followed by the present participle form of the verb "sleeping." This structure is known as a present continuous tense.

Understanding the Present Continuous Tense:
The present continuous tense is used to describe actions that are happening at the current moment or around the present time. It is formed by using the present tense of the verb "to be" followed by the present participle form of the main verb.

Subject-Verb Agreement:
In English grammar, the verb must agree with the subject in terms of number and person. In the given question, the subject is "you," which is the second-person singular or plural pronoun. When using the present continuous tense with "you," the correct form of the verb to be is "are." Therefore, the correct statement is "Are you sleeping?"

Present Continuous Tense Structure:
To form the present continuous tense, we follow this structure:
- Subject (You) + Present Tense of "to be" (Are) + Present Participle (Sleeping).

Example Usage:
Here are a few examples of how the present continuous tense is used in different situations:

1. Describing Actions in Progress:
- "I am studying for my exams right now."
- "She is cooking dinner at the moment."
- "They are playing football in the park."

2. Future Arrangements:
- "We are meeting for lunch tomorrow."
- "He is flying to London next week."
- "Are you coming to the party on Saturday?"

3. Temporary Situations:
- "He is staying with us for a few days."
- "She is working at a different office this week."
- "Are you living in the city temporarily?"

Conclusion:
When answering the question "Are you sleeping?" with the correct form, we use the present continuous tense structure: "you sleeping." This structure follows the subject-verb agreement rules and is used to describe actions happening at the present moment or around the present time. It is essential to understand the correct usage of the present continuous tense when communicating in English.