The correct option is E ACBA
We are aware that in the series,, a particular sequence is getting repeated.
The sequence is A...BBC...AAB...CCA...BBCC
We notice that if the sequence (A...BBCC) repeats, then it is consistent for the first 6 characters too.
This will automatically give Blank 2=C and Blank 3=B
So, the sequence becomes
A...BBCCAABBCCA...BBCC
Just mere observation gives Blank 1=A and Blank 4=A
So the Answer becomes ACBA
Thus, option E is the answer.