If D is the daughter of A, D is the sister of M and A's brother is C, how are C and M related?

In the following Blood relation diagrams,
Square is represented as Male.
Circle is represented as Female.
Double horizontal line is represented as couple.
Single horizontal line is represented as sibling.
Vertical line is represented as Mother/Father/Son/Daughter.

So, As we can see Genders are not mentioned for A and M So we didn't mark it .
According to this C is uncle of M 
Hence, Option B Uncle And Niece is correct.