To calculate the cost of 18 ounces of peanut butter at $0.20 per ounce, you can follow these steps:
1. Multiply the cost per ounce ($0.20) by the number of ounces (18):
$0.20 * 18 = $3.60
Therefore, 18 ounces of peanut butter would cost $3.60.
Therefore, the correct answer to the question is:
C) $3.60