Which of the following is not a statement.

Options

A. 2 is an odd number
B. 10 is less than 8
C. the number 13 is prime
D. please do me a favour

Explanation

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

Let's analyze each option step by step:

1. **Option 1: "2 is an odd number."**
- This statement can be evaluated. The number 2 is not an odd number; it is an even number. Therefore, this statement is false.

2. **Option 2: "10 is less than 8."**
- This statement can also be evaluated. The number 10 is greater than 8, so this statement is false.

3. **Option 3: "The number 13 is a prime number."**
- This statement can be evaluated as well. The number 13 is indeed a prime number (it has no divisors other than 1 and itself). Therefore, this statement is true.

4. **Option 4: "Please do me a favour."**
- This is not a declarative sentence that can be evaluated as true or false. It is a request or an imperative statement, which does not fit the definition of a mathematical statement.

Based on this analysis, we conclude that **option 4** is not a statement.

### Final Answer:
**Option 4: "Please do me a favour." is not a statement.**