Question

which invention was most important in revolutionizing the meat industry?
air brakes
knuckle couplers
the pullman car
the refrigerator car

Explanation:

Air brakes are for train - stopping, knuckle couplers connect train cars, Pullman car is a passenger car. Refrigerator car allowed for long - distance transport of meat without spoilage, revolutionizing the meat industry.

Answer:

the refrigerator car