How many primes less than $100$ have $7$ as the ones digit? (Assume the usual base ten representation) 
$\text{(A)} \ 4 \qquad  \text{(B)} \ 5 \qquad  \text{(C)} \ 6 \qquad  \text{(D)} \ 7 \qquad  \text{(E)} \ 8$
List out all numbers that have 7 as the ones digit less than 100: ${7, 17, 27, 37, 47, 57, 67, 77, 87, 97}$. Only $7, 17,37, 47,67,$ and $97$ are prime. Thus, it is $\boxed{C}$. -slackroadia