The answer is the G1 checkpoint
12-A
15-B
11-C
6-D
1-E
10-F
8-G
9-H
5-I
3-J
7-K
14-L
4-M
13-N
2-O
I'm not 100% sure, but I think that the digestive system excretes solid wastes only and the excretory system excretes liquid wastes only. So the 3rd option is probably correct.
The answer would still be ACC
