Captains of industry like steel magnate andrew carnegie and oil man john d. rockefeller:
a. voluntarily provided important resources to the war effort.
b. made millions bilking southerners who were buying war bonds.
c. became important advisers to president lincoln.
d. began creating or consolidating their fortunes during the civil war.
e. benefited after the war from the respect their military service earned for them.

The correct answer is letter "D": began creating or consolidating their fortunes during the Civil War.

Explanation:

American Civil War (1861-1865) was one of the bloodiest conflicts over slavery held between the northern and the southern states. Eventually, the Confederate States -pro-slavery states, surrendered at the cost of more than 620 000 deaths over the 4 years the war lasted.  

During the war years personalities such as Andrew Carnegie (1835-1919) and John D. Rockefeller (1839-1937) consolidated their fortunes since the first, and iron businessman and the second, oil investor, saw a rise in the demand of their goods because of their need in the battlefield -armors for gunboats, cannons and frames.

answer; presidential election years;