Use some reasoning:

We know the products are greater than 15, but less than 200.
The lower bound is easy:
If the lowest card were 3, then one of the products would be 12 as 3*4 is 12. Therefore, the lowest card can be 4 - 4*5 is 20, which is over 15.
The upper bound:
Since we know that 15 times 15 is 225, we should try numbers that are near by.
Clearly 15 wont work, since 15*15 is 225, and 15*16 would be larger than that.
14 also does not work as 14*15 is 210, which is greater than 200
So the max card can be 13.

C.