Which form of communication was introduced in the 19th century and is still widely used in the twenty first century?

The form of communication introduced in the 19th century that is still widely used to this day is the telegraph.

Explanation:

In 1837, photographer and painter Samuel F. B. Morse created the first telegraph, in addition to creating an alphabet to transmit the information that would later bear his name, the Morse code.

Both the device and the alphabet began to be used 7 years after its invention. The first communication was made between Washington and Baltimore, separated by only 40 miles.

Telegrams are still used mainly for important notifications since these arrive physically to the receiver.

i think the answer is c, rivers.

explanation:

sometimes, borders fall along natural boundaries like rivers or mountain ranges. for example, the boundary between france and spain follows the crest of the pyrenees mountains. for part of its length, the boundary between the united states and mexico follows a river called the rio grande. the borders of four countries divide africa’s lake chad: niger, chad, cameroon, and nigeria.

d will be ur answer

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