Which of the following is not a statement ?

Options

A. Every set is a finite set
B. 18 is multiple of 6
C. Prime numbers are irrational numbers
D. None of these

Answer

To determine which of the given options is not a statement, we need to analyze each option to see if it can be classified as either true or false. A statement is defined as a declarative sentence that can be classified as true or false.

### Step-by-Step Solution:

1. **Option 1: "Every set is a finite set."**
- This statement is false because there are infinite sets (e.g., the set of all natural numbers). Since it can be classified as false, it is indeed a statement.

2. **Option 2: "18 is a multiple of 6."**
- This statement is true because 18 can be expressed as 6 multiplied by 3 (6 × 3 = 18). Since it can be classified as true, it is also a statement.

3. **Option 3: "Prime numbers are irrational numbers."**
- This statement is false because prime numbers are defined as natural numbers greater than 1 that have no positive divisors other than 1 and themselves. Irrational numbers, on the other hand, cannot be expressed as a fraction of two integers. Since this statement can be classified as false, it is a statement.

4. **Option 4: "The sky is blue."**
- This statement is generally true, as the sky appears blue during the day due to Rayleigh scattering. Since it can be classified as true, it is also a statement.

5. **Conclusion:**
- All the options provided are statements because they can be classified as either true or false. However, if one of the options were to be a question or an expression that doesn't have a truth value (like "What is the color of the sky?"), that would not be a statement.

### Final Answer:
Since all the options provided are statements, we need to identify if there is an option that does not fit this criterion. If all options are true or false, we conclude that none of them is not a statement.