Final answer:
Joshua Chamberlain held Little Round Top during the Battle of Gettysburg in the Civil War. Abraham Lincoln's opponent in the 1864 Presidential election was General McClellan.
Step-by-step explanation:
The individual who held Little Round Top during a critical Civil War battle was b) Joshua Chamberlain. He was a Union army officer and is best known for his valor and strategic defense of Little Round Top at the Battle of Gettysburg. This defensive action was pivotal in the Union Army's victory during the battle.
Regarding the 1864 Presidential election, Abraham Lincoln's opponent was c) General McClellan, not General Grant, General Sherman, or General Lee. Lincoln won reelection, which allowed him to continue pursuing the Union campaign until the Confederacy's surrender to Union general Grant at Appomattox Court House.