Which of the following is not a statement

Options

A. Brush your teeth
B. 11 is a prime number
C. `sqrtp` is an irrational number, if p is prime
D. 15 is composite number

Answer

To determine which of the following is not a statement, we need to understand what a statement is in mathematical reasoning. A statement is a declarative sentence that is either true or false, but not both.

Let's analyze the options one by one:

1. **Brush your teeth.**
- This is an imperative sentence, which gives a command or request. It does not assert a fact that can be classified as true or false. Therefore, this is **not a statement**.

2. **11 is a prime number.**
- This is a declarative sentence that can be evaluated. Since 11 has only two factors (1 and 11), this statement is true.

3. **√p is an irrational number if p is prime.**
- This statement can also be evaluated. If p is a prime number, then √p cannot be expressed as a fraction of two integers, making it an irrational number. Thus, this statement is true.

4. **15 is a composite number.**
- This statement is also evaluable. A composite number has more than two factors. Since 15 has factors 1, 3, 5, and 15, it is indeed a composite number, making this statement true.

After evaluating all the options, we conclude that the first option, "Brush your teeth," is not a statement.

### Final Answer:
The option that is not a statement is **"Brush your teeth."**