We can immediately confirm C is TRUE because the base is simply 5x5=25 square inches.
Now looking at A, the definiton of "slant height" is that if you ran a ruler up one of the sides of the pyramid, thats it. So imagine building this net, the red line would be referring to the slant height, A is TRUE.
Answer: B is NOT TRUE.
In fact, the equation of the surface of the pyramid is far more complicated than the one proposed in the question. For reference, the area of a pyramid is given by:
[tex]A=lw+l \sqrt{ \frac{w}{2} ^{2} + h^{2} } +w \sqrt{\frac{l}{2} ^{2} + h^{2}} [/tex]
