The Pony Express Chapter I
At A Nation's Crisis

The Pony Express was the first rapid transit and the first fast mail line across the continent from the Missouri River to the Pacific Coast. It was a system by means of which messages were carried swiftly on horseback across the plains and deserts, and over the mountains of the far West. It brought the Atlantic coast and the Pacific slope ten days nearer to each other.

It had a brief existence of only sixteen months and was supplanted by the transcontinental telegraph. Yet it was of the greatest importance in binding the East and West together at a time when overland travel was slow and cumbersome, and when a great national crisis made the rapid communication of news between these sections an imperative necessity.

Read the sentence from the Pony Express excerpt:

The Pony Express was the first rapid transit and the first fast mail line across the continent from the Missouri River to the Pacific Coast.

In using this sentence to introduce the Pony Express in chapter one, the author

A) explains the importance of the subject
B) argues in favor of the subject
C) describes the impact of the subject
D) identifies the subject