Hi I'm a 1700-1800 on this site and I have a repertoire hole as black I play e5 against 1 e4 and the grunfeld against 1 d4.
Is your question what to play against 1 c4? 1..Nf6 is the most popular choice.
(I figured that since you only go one move deep against d4 and e4, I assume you only want to know one move deep on 1 c4.)
Hi I'm a 1700-1800 on this site and I have a repertoire hole as black I play e5 against 1 e4 and the grunfeld against 1 d4.