Consider alphabet Σ = {a, b}, the null/empty string λ and the set of strings X0, X1, X2 and X3 generated by the corresponding non-terminals of a regular grammar X0, X1, X2, and X3 are related as follows:
Which one of the following choice precisely represents the string in X1 ∪ X2?
A b*a b*a b*a b*
B (a + b)*
C b* a (a + b)*
D b*a b* a b*
answer given is c but how becz c is representing x0........please check