A five-legged Martian has a drawer full of socks, each of which is red, white or blue, and there are at least five socks of each color. The Martian pulls out one sock at a time without looking. How many socks must the Martian remove from the drawer to be certain there will be 5 socks of the same color?

$ \textbf{(A)}\ 6\qquad\textbf{(B)}\ 9\qquad\textbf{(C)}\ 12\qquad\textbf{(D)}\ 13\qquad\textbf{(E)}\ 15 $
To determine the minimum number of socks the Martian must remove to be certain there will be 5 socks of the same color, we need to consider the worst-case scenario. 

1. **Identify the worst-case scenario:**
   - The Martian could pick socks in such a way that he avoids getting 5 socks of the same color for as long as possible.
   - This means he could pick up to 4 socks of each color without having 5 socks of any one color.

2. **Calculate the number of socks in the worst-case scenario:**
   - If the Martian picks 4 socks of each color, he will have:
     \[
     4 \text{ (red)} + 4 \text{ (white)} + 4 \text{ (blue)} = 12 \text{ socks}
     \]
   - At this point, he has 4 socks of each color, but not 5 socks of any one color.

3. **Determine the next sock:**
   - The next sock he picks (the 13th sock) will necessarily be the 5th sock of one of the colors, because there are only 3 colors and he already has 4 socks of each color.

Therefore, the Martian must remove at least 13 socks to be certain that he will have 5 socks of the same color.

The final answer is $\boxed{13}$