In order to find this, calculate out the discriminant for each of the following equations. If the discriminant is a perfect square, then it can be factored.
Discriminant = b^2 - 4ac
The only of the equations that does not yield a perfect square is B. The work for it is done below for you.
Discriminant = b^2 - 4ac
Discriminant = 7^2 - 4(2)(-5)
Discriminant = 49 + 40
Discriminant = 89
Since 89 is not a perfect square, we cannot factor this.