First, let's have a look at the candidate keys.
In this case the candidate keys are $\rightarrow$ $CDA$, $CDB$, $CDE$.
Now, in this case, each attribute is a prime attribute. So, this realtion is already in 3NF and there is no point in decomposing this further.
Therefore, no additional relations are required.
So, the correct answer to this question will be 0.