Which excerpt from fast food nation best states a reason supporting the author’s claim that fast food restaurants follow the assembly line model? a: once an order has been placed, buttons light up and suggest other menu items that can be added. b: at burger king restaurants, frozen hamburger patties are placed on a conveyer belt and emerge from a broiler ninety seconds later fully cooked. c: the mcdonald’s operations manual today has ten times the number of pages and weighs about four pounds. d: is incorrect

Short answer B
Argument
It isn't C either. Any number of reasons could be the cause of a book that size. Taking care of the building alone would result in a huge number of pages that don't really concern anyone but the owner and the person responsible for taking care of the building. Tax deductions would be another problem and so would overtime and reporting methods. 

Assembly lines methods have nothing to do with lights that offer options to the basic model of anything being made assembled or manufactured. Not in the way fast foods would use the term.

The answer is B. The object is to get the hamburgers cooked. Knowing that the process takes 90 seconds and they start frozen, go onto a conveyor belt and come out cooked is so typical of assembly line methods.