There is no immediate left recursion, but there is left recursion as can be seen below.
A -> Br | x
B -> Cs | y
C -> At | z
Thus, C -> Brt | xt | z => C -> Csrt | yrt | z| xt . This shows left recursion.
Now remove left recursion from C -> Csrt | yrt | z | xt.
C -> yrtC' | zC' | xtC'
C' -> srtC' | $\epsilon$