What was the cost of the spencer repeating rifle?

At first, the view by the Department of War Ordnance Department was that soldiers would waste ammunition by firing too rapidly with repeating rifles, and thus denied a government contract for all such weapons. (They did, however, encourage the use of carbine breechloaders that loaded one shot at a time. Such carbines were shorter than a rifle and well suited for cavalry.)[8]More accurately, they feared that the armies logistics train would be unable to provide enough ammunition for the soldiers in the field, as they already had grave difficulty bringing up enough ammunition to sustain armies of tens of thousands of men over distances of hundreds of miles. A weapon able to fire several times as fast would require a vastly expanded logistics train and place great strain on the already overburdened railroads and tens of thousands of more mules, wagons, and wagon train guard detachments. The fact that several Springfield rifle-muskets could be purchased for the cost of a single Spencer carbine also influenced thinking.[9] However, just after the Battle of Gettysburg, Spencer was able to gain an audience with President Abraham Lincoln, who invited him to a shooting match and demonstration of the weapon on the lawn of the White House. Lincoln was impressed with the weapon, and ordered Gen. James Wolfe Ripley to adopt it for production, after which Ripley disobeyed him and stuck with the single-shot rifles.[1][10]

The answer is option c.