The stars . . . . . counted.

Solution (By Examveda Team)

The correct sentence is: "The stars cannot be counted."
This is because the sentence requires a passive voice construction, and the context refers to the impossibility of counting the stars due to their vast number.
“Cannot be” is a modal verb phrase used to express impossibility in the passive voice.
Hence, "cannot be counted" correctly conveys that it is not possible to count the stars.

Explanation of Incorrect Options:
Option A: can
"Can" alone is an active voice modal verb and needs to be followed by a base verb.
"The stars can counted" is grammatically incorrect because it lacks the auxiliary verb "be" for passive voice.
It would need to be "can be counted" to be correct, but even then, it would be factually wrong in this context.
Option B: can be
"Can be counted" is grammatically correct and in passive voice.
However, it implies that stars are countable, which is not true considering the vastness of the universe.
So while grammatically acceptable, it is contextually incorrect.
Option D: must
"Must" indicates necessity or obligation, and using it without "be" is grammatically wrong.
"The stars must counted" is incorrect; it should be "must be counted" to be in correct passive form.
Even then, the sentence "The stars must be counted" implies an obligation, which is illogical and contextually inappropriate.

Therefore, only Option C: cannot be correctly fits both the grammatical structure and meaning.