None of your choices provide the correct solution to what you have written!
3n+2 + 3n+3 - 3n+1 → 3n+1(31 + 32 - 30) → 3n+1(3 + 9 - 1) → 11*3n+1
I think you must have meant 3n+2 / (3n+3 - 3n+1) → 31 / (32 - 30) → 3 / (9 - 1) → 3/8 (where 3n+1 has been factored out of the terms in both numerator and denominator).