Which innovation extended the number of hours in a day that Americans could work and play?

A. Bessemer process

B. telegraph technology

C. refrigeration

D. electricity

The correct answer is D. Electricity. It made it possible because work could be done under lights for example so you didn't have to use candles or catch daylight or things like that. Also, they could use their leisure time for things more because they had lights so they could read or play or anything similar without using candles.