If you grew up with Abraham Lincoln, you would have seen great changes take place between the time Lincoln was a boy in Kentucky and the time he was president in Washington, D. C. Important changes took place in transportation and communication. When Lincoln was a boy, there were no trains. Mail that had to be delivered across long distances was carried by horse or a vehicle pulled by horse. It took a long time for a message to travel by stagecoach. By the time Lincoln was a grown man, people communicated using the telegraph, which was like an early version of the phone. It allowed messages to be sent very quickly.
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"By the time Lincoln was a grown man, people communicated using the telegraph, which was like an early version of the phone."

What type of context clue is used to help you define the word telegraph?
A.
explanation
B.
antonym
C.
example
D.
synonym