method 1: draw the DFA and then derive reg ex from it
method 2: by verification
option a. does n't generates strings ending with 0 ex:1100
option c :does n't generates strings like 110011,1101111,011011,...i.e it does n't producing 0 between 2nd 1 and 3rd 1 in the string
option d: does n't generate $\epsilon$
option b: is the answer