Re: Each of the integers from 1 to 20 is written on the a separate index card and placed in a box. If the cards are draw

The integers from 1-20 contain 10 even and 10 odd numbers

As soon as we pick an even number, we know that the product will be even too. Therefore the "worst case" scenario is if we pick all 10 odd evens first and only get an even number on the 11th pick.

The answer is therefore 11! (C)