Answer:
D. 29
Explanation:
If the class sold 145 boxes of cookie dough in the first month and 76 boxes in the second month, we can add these together and total, they have sold 221 boxes of cookie dough. You then subtract 221 from 250 (250 - 221) and you wind up with 29 boxes of cookie dough, which is how many more boxes they need to sell.