D, because it's a full sentence.
<h2><em>I think it may be D location </em></h2>
Answer with Explanation:
Transportation innovation greatly contributed to the <em>American national unity </em>by uniting the nations that were growing during those times. It provided an ease when it comes to <u>trading </u>because goods from the different cities and towns were travelled/transported through newly built<em> transportations.</em>
An example of this is the "steamboat" which was first used in the<em> Hudson River </em><em>(1807). </em>This hastened the trading which navigated the rivers, thereby <em>lessening the cost.</em>
Another example is the "steam railroads"<em> (1830). </em>These didn't only helped with the trading but also started carrying passengers who wanted to travel from one place to another. They successfully<u> replaced the use of horses.</u>
Such transportations grew and connected the whole country, especially in terms of <em>economy, culture and politics.</em>
The <u>EPA</u> also ensures that all communities have access to accurate information about the environment.