Martians measure angles in clerts.  There are $500$ clerts in a full circle.  How many clerts are there in a right angle?
$\text{(A)}\ 90 \qquad \text{(B)}\ 100 \qquad \text{(C)}\ 125 \qquad \text{(D)}\ 180 \qquad \text{(E)}\ 250$
The right angle is $1/4$ of the circle, hence it contains $500/4=125\rightarrow \boxed{\text{C}}$ clerts.