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.
1. do you walk, I'm not going, is raining
2. is Boris doing, is watching
3. do your parents work, visit, have
4. is looking, do you know, doesn't sleep
5. am waiting, do you know, is studying
6. do you want, I'm looking after
The subjects of the sentence are C and D.
