A. Grass is not eaten by a lion, however hungry he may be.
B. Grass is not being eaten by a lion, however hungry he may be.
C. Grass is eaten not by a lion, however hungry he may be.
D. Grass is being not eaten by a lion despite being hungry.
Given sentence is in simple present tense and it is in active voice.
Rule :
Subject + (is/am/are) + V3 + Other agents