Which one of the foliowing RE represent the language: the set of all binary strings having two consecutive 0s and two consecutive 1s?
a) (0+1)*0011(0+1)*+(0+1)*1100(0+1)*
b)(0+1)*(00(0+1)*11+11(0+1)*00)(0+1)*
c) (0+1)*00(0+1)*+(0+1)*11(0+1)*
d)00(0+1)*11+11(0+1)*00
