Whose work on the steam engine made steam the main source of power during the industrial revolution

James Watt.

Explanation:

James Watt was a Scottish engineer who invented a new type of steam engine that laid the foundations for the industrial revolution in the 18th century.

Watt, who had learned to be a tool master, was once brought to repair a steam engine made by Thomas Newcomen. He studied Newcomen's model carefully and found that using steam to propel the machine was a good idea, but made sure that Newcomen's solution was not the most successful - the machine had low performance and high fuel consumption. Watt improved the machine for ten years and eventually made a much more efficient steam engine.  

His steam engine revolutionized British industry. Steelmakers used his machine to drive large hammers; In the textile industry, it was used to power new spinning machines; And in the coal mines, people no longer had to carry coal bags to the ground, because the work was now done by a drive powered by a Watt steam engine.

use wikipedia, i think they have this.

the answer is c. to explore the louisiana purchase