If the third digit of an acceptable product code is not 0, which one of the following must be true?

Hi, for question 4 concerning the product code order, if zero was no acceptable as the third digit, then why would 1, 2, 3, 0, 4 not work? Considering the rules are 1. Each number is used once 2. 2nd number is twice as much as the first (1+1=2) 3. The 3rd number is less than the 5th (3<4) Subset:. Zero cannot be 3rd Please if someone could clarify where I went wrong