Change killer’s to killers
For the adjective meaning deficient or lean, meager is the preferred spelling in American English. Meagre is preferred in all other varieties of English. Other than the spelling, there is no difference between the two forms.
The correct answer is D.
We can clearly see that Gilgamesh and Enkidu were triumphant in their battle against Humbaba because Gilgamesh is carrying his head. They killed to monster and chopped his head off in order to show it as proof of their victory. Only in option D do we see the result of their battle, which they won.
A. The answer is A because D and C are incomplete, and B has improper grammar, being there is a comma after the game makes it incorrect.