The correct answer is A. Grass is not eaten by a lion, however hungry he may be.
The sentence “Lion does not eat grass, however hungry he may be” is in the present tense. The verb “eat” is in the negative form, and the subject “lion” is singular. The sentence is also in the active voice, meaning that the subject is doing the action.
The sentence can be paraphrased as “A lion does not eat grass, no matter how hungry he is.” This means that lions are not herbivores, and they do not eat grass as part of their diet. Even if a lion is very hungry, it will not eat grass.
The other options are incorrect because they do not accurately reflect the meaning of the original sentence. Option B, “Grass was being not eaten by a lion, however hungry he may be,” is in the past tense. Option C, “Grass is eaten not by a lion, however hungry he may be,” is in the passive voice. Option D, “Grass is not being eaten by a lion, however hungry he may be,” is also in the present tense, but it does not accurately reflect the meaning of the original sentence. The original sentence states that lions do not eat grass, while Option D states that grass is not being eaten by lions.