Elevated trains and subways improved travel by using horses and carriages to increase speed. making the car unnecessary in urban areas helping people travel from one city to another moving commuters without crowding city streets.

## Step 1<br />The problem is a multiple-choice question about the impact of elevated trains and subways on travel. The options provided are:<br />A. using horses and carriages to increase speed.<br />B. making the car unnecessary in urban areas.<br />C. helping people travel from one city to another.<br />D. moving commuters without crowding city streets.<br /><br />## Step 2<br />We need to analyze each option in relation to the question. The question is asking about the benefits of elevated trains and subways.<br /><br />## Step 3<br />Option A is incorrect because elevated trains and subways do not use horses and carriages. They are powered by electricity or other means.<br /><br />## Step 4<br />Option B is also incorrect. While elevated trains and subways can reduce the number of cars on the road, they do not make cars unnecessary in urban areas.<br /><br />## Step 5<br />Option C is not correct either. Elevated trains and subways are typically used for intra-city travel, not inter-city travel.<br /><br />## Step 6<br />Option D is the correct answer. Elevated trains and subways move commuters without crowding city streets. This is one of the main benefits of these transportation systems. They allow for faster and more efficient travel without the congestion of surface streets.