Answer
The answer is below.
Work Step by Step
We know:
$T=2\pi\sqrt{\frac{L}{a}}$
Thus, we find:
a) $T=2\pi\sqrt{\frac{L}{g}}$
b) $T=2\pi\sqrt{\frac{L}{\frac{1}{2}g}}=2\pi\sqrt{\frac2{L}{g}}$
c) $T=2\pi\sqrt{\frac{2L}{3g}}$
d) This is the same as dividing by 0, so the period is infinite or undefined (either is correct).
