About "2"

It's all of the above!

1) 2 is a prime since it is only divisible by itself and 1.

2) 2 is a rational number since it is expressible as $\frac{p}{q} = \frac{2}{1}$ .

3) 2 is an even number since $2 \equiv 0 (mod 2)$ .

4) 2 is real number since it is rational (per #2) $\Rightarrow \mathbb{Q} \subseteq \mathbb{R}$ .

5) 2 is an integer since it is rational (per #2) $\Rightarrow \mathbb{Z} \subseteq \mathbb{Q}$ .

6) 2 can be used as a constant for an infinite number of equations (for example the circular equation $x^2 + y^2 = 2$ ).

as 2 is a prime number. it must "it's all of the above"

How do you define 'Above'? ;-) "Can be used as a constant" is under the the option "All of the above".