Solution

The given grammar is:

S → SbS | a

The string abababa can be derived using the:

(A) two parse trees 

(B) two left most derivative

First derivative

S → SbS

S → SbSbS

S → SbSbSbS

S → abSbSbS

S → ababSbS

S → abababS

S → abababa

Second derivative

S → SbS

S → abS

S → abSbS

S → ababS

S → ababSbS

S → abababS

S → abababa

(C) two right most derivative

First derivative

S → SbS

S → SbSbS

S → SbSbSbS

S → SbSbSba

S → SbSbaba

S → Sbababa

S → abababa

Second derivative

S → SbS

S → Sba

S → SbSba

S → Sbaba

S → SbSbaba

S → Sbababa

S → abababa

Hence, the correct answer is options 1.