Answer the following question given this paragraph: 

A: With greater reflection off the ionosphere, AM waves can travel even farther at night than they can during the day. Radio receivers can often pick up radio broadcasts at night from cities that are hundreds of miles away.


Q: Greater reflection off what atmospheric layer allows am radio waves to travel even farther at night than they can during the day?

 Choices:

- stratosphere

- exosphere

- troposphere

- ionosphere

A:
ionosphere
