The Good Chocolate Company makes a variety of chocolate candies, including a 12-ounce chocolate bar (340 grams). The output of the machine that fills the bar molds is approximately normal with a mean of 340 grams and a standard deviation of 1.5 grams. If the specifications for the 12-ounce chocolate bar are 332 grams to 348 grams, what is the process capability index?
A) 1.78
B) 0.56
C) 0.90
D) 2.22