The Difference Between a Three-Digit North American Industry Classification System

The difference between a three-digit North American Industry Classification System (NAICS) industry and a six-digit NAICS industry is that:

A) the three-digit industry is more specifically defined than the six-digit code.
B) the six-digit industry is more specifically defined than the three-digit code.
C) three-digit codes apply to a different set of industries than six-digit codes.
D) three-digit codes are used to classify industries whereas six-digit codes are used to classify firms.