In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Among the entities, try to find the best entity that is most likely to fill in "_" and classify the answers based on options.

(CNN) Hunkered in a Vietnam bunker, with rockets and mortar shells raining down, the two Marines made a pact. It was New year's Eve, 1968. And they promised that if they survived the war and made it home alive, the two would call each other every New Year's Eve. And they did. For nearly half a century, Master Sgt. William Cox and Sgt. James Hollingsworth checked up on each other. But on Sunday, Cox will ring in the New Year alone. His friend "Hollie" died in October. He was 80 years old. A promise made Cox and Hollingsworth flew missions together as helicopter door gunners. On the ground in Vietnam, Hollingsworth helped maintain the choppers. Cox kept track of ammunition.William Cox and James Hollingsworth make pact in Vietnam bunkerFor first time in half century, old marine marks New Year's without buddy 
 Questions:He ended the eulogy with a phrase the two used to repeat: "_, you keep 'em flying, and I'll keep 'em firing." (A) Vietnam (B) Marines (C) William Cox (D) James Hollingsworth (E) Cox (F) New Year (G) Hollie
(G)