As far as the children (A and B) are concerned:

Question

a) A and B will be regarded as children born of unmarried parents
b) A and B will be regarded as children born of married parents
c) only Y will have full parental responsibilities and rights in respect of A and B unless
a court orders otherwise
d) both Y and Z will have full parental responsibilities and rights in respect of A and B
unless a court orders otherwise

Answer 1

c) only Y will have full parental responsibilities and rights in respect of A and B unless a court orders otherwise.