Why is it mandatory to use or connect a level translator circuit after the intermediate stage in a typical operational amplifier?

Why is it mandatory to use or connect a level translator circuit after the intermediate stage in a typical operational amplifier ?

a. For Phase level shifting
b. For DC level shifting
c. For AC level shifting
d. Both A.C. & D.C. Level shifting.

Correct Answer : b. For DC level shifting

Explanation :

Level shifter or translator is usually connected in a typical Op-Amp so as to shift the D.C. Level at the output of intermediate stage which is grounded onward to zero. Intermediate stage is basically a differential amplifier which is driven by the previous state output. The D.C. Level at the output of intermediate stage is good above ground potential in case of direct coupling. Hence, it is obligatory to use the level shifter in OP-Amps.