Answer:
C. to start cotton plantation
Explanation:
People moved to the west in the<em> mid-1800s</em> due to the "Homestead Act" that was signed by President Abraham Lincoln. This act distributed the wild lands to people thus, <u>giving them the opportunity to have a</u><u> free land</u><u> which they could cultivate.</u> This makes letter A (to obtain free land) as one reason.
It was, supposedly, an opportunity for different individuals such as<em> farmers, cowboys and miners.</em> Many people were driven to the west in search for gold, silver and copper. This makes letters B (to establish cattle ranches) and D (to prospect for gold) as other reasons.
However, it became harder for American farmers to grow crops. Plantation was mainly focused on <em><u>wheat and corn.</u></em> So, this makes letter C (to start cotton plantation) as incorrect.