The correct answer is: 
C) f(x)=|42.67-x|. 
Step-by-step explanation: 
Production will be stopped if the difference in diameter is greater than 0.002 mm. 
This difference can mean that the golf ball has a diameter more than 0.002 larger than 42.67 mm, or a diameter more than 0.002 smaller than 42.67. This is the reason for using an absolute value function. 
 Absolute value represents the distance a number is from 0. For this function, we would want only the values where the function is less than 0.002.