I can't figure out how to get the process width from the following information....

Suppose your manager presents you with the following information about machines that could be used for a job, and wants your recommendation on which one to choose. The specification width is .48 mm. In this instance, you can narrow the set of choices, but you probably wouldn't make a recommendation without an additional piece of information

machine Cost Per Unit Std Dev

A 14 0.068

B 12 0.06

C 18 0.051

D 10 0.063