HELP! How did the multiplex telegraph change communication in the 1800s?

It helped trains run on schedule and avoid collisions.
It made it possible to use Morse code with telegraphs.
It helped telegraphs transmit messages at a faster rate.
It allowed people to communicate using speech alone.

A.)  It helped trains run on schedule and avoid collisions.

Explanation:

Woods created the multiplex telegraph in 1887, and this was a device that helped telegraphs work on moving trains. Woods' invention helped trains to communicate, and this meant that they could run on a schedule and avoid crashing into one another.