What led to the communist guerilla forces being defeated during the Greek Civil War?

Adepleting reserves of the Greek government
Bsupport from non-communist neighboring countries
Ca military attack by Soviet armed forces
Dan intervention by the United Nations

Verified Answer :

It's D 

The UN stepped in to do an investigation to find out whether or not neighboring countries were aiding guerilla

The Answer is D. an intervention by the United Nations. The UN found out communist countries were aiding the Greek communist revolutionaries, and stepped in to cut the supplies. Then the Greek government quickly ended the Communist uprising.