Question

Which advance made a network of railroad lines possible? a. the air brake c. the convertible berth b. a standard gauge d. the dining car Which advance made a network of railroad lines possible?

a. the air brake
c. the convertible berth
b. a standard gauge
d. the dining car

pls help

Answer 1

A.

Explanation: because I just did the quiz and got it right

Answer 2

A standard Gauge

Step-by-step explanation:

I think thats right