Final answer:
The major incentive to build the Transcontinental Railroad was to link the mining industry's mines with production centers and to increase the value of government lands.
Step-by-step explanation:
A major incentive to build the Transcontinental Railroad was the need for a comprehensive transportation system that could support the nation's commercial activity and development, especially in connecting the vast resource-rich West with the rest of the country. The mining industry required an efficient transportation system to link mines with production centers, and the government knew that connecting the coasts would greatly increase the value of its lands, leading to higher revenue from land sales. Moreover, President Lincoln during the Civil War was interested in facilitating the westward movement of White settlers who opposed slavery.
Therefore, the correct answer to which of the following was a major incentive to build the Transcontinental Railroad is: C) The mining industry needed a transportation system to link mines with production centers.