Chloe is buying candies at a grocery store. She can either spend $8$ dollars on a $15\text{-ounce}$ bag or $12$ dollars on a $20\text{-ounce}$ bag. Which is a better buy? 
选项为:A:The $15\text{-ounce}$ bag  B:The $20\text{-ounce}$ bag  请回答其中一个选项.