Change the following sentence into passive form-
The grandmother feeds the sparrows daily.
a) The sparrows are fed by the grandmother daily.
b) The sparrows are fed up by the grandmother daily.
c) The sparrows are feed by the grandmother daily.
d) None of the above.

Hint:A passive voice is a form or set of a verb in which the subject undergoes the action of the verb. For example, they were killed as opposed to the active form of he killed them.

Complete answer:
While converting a sentence into passive form, one must make the object of the active sentence into the subject of the passive sentence, use the verb “to be” in the same tense as the main verb of the active sentence. We have to convert the given sentence into a passive form.
Now, let us examine all the given options to find out the correct option :
Option ‘a' is The sparrows are fed by the grandmother daily. This is the correct option as the verb and tense of the active form is correctly converted to passive form.
Option ‘b' is The sparrows are fed up by the grandmother daily. Here, “fed up” is used. It literally means – annoyed, unhappy, or bored. This will completely change the meaning of the given sentence, so this cannot be the correct answer.
Option ‘c’ is The sparrows are feed by the grandmother daily. This option cannot be the correct option as ‘feed’ cannot be used here. Only past tense is used while such types of passive sentences.
Option ‘d’ is None of the above. This option is applicable only if all the above options seem incorrect.
As we have analyzed all the given options, we can easily figure out the correct answer. Here, the correct form of the passive sentence is – The sparrows are fed by the grandmother daily. Hence, the option 'a' is the correct option.

Note:
Pay attention to the tense of the verb. Those are the main part of any given sentence when it comes to changing its forms. Here, the past tense of ‘feed’ has to be used in the passive form of the given sentence.