The correct answer is C.
There were two major fronts during the Second World War. The European Front was where the allied forces fought Germany and the Pacific Front was where the USA got involved after Japan attacked Pearl Harbor in 1941.
On the European front, America fought to eliminate the government of Nazi Germany and stop the holocaust of millions of Jews. On the Pacific one, the Pearl Harbor attack forced the United States to declare war on Japan. Four days later, Germany and Italy declared war on the United States, drawing the country into two-theater war.
U.S. ground forces were used in Europe while the Pacific Theater was mainly a naval and aerial battle.