Select the correct passive form of the given sentence.

A large number of people are using internet banking these days.

Internet banking is being used by a large number of people these days.

The correct passive form of the given sentence is Internet banking is being used by a large number of people these days.

The active voice of the sentence is A large number of people are using internet banking these days. This sentence is in the present progressive tense, which is used to describe an action that is happening now or that is happening repeatedly. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the present participle of the main verb. In this case, the subject of the active sentence is "a large number of people" and the main verb is "use." The present participle of "use" is "using." So, the passive form of the sentence is Internet banking is being used by a large number of people these days.

The other options are incorrect because:

• Internet banking is using a large number of people these days. is in the active voice, not the passive voice.
• Internet banking has been used by a large number of people these days. is in the past perfect tense, while the original sentence is in the present progressive tense.
• Internet banking is used by a large number of people these days. is in the simple present tense, while the original sentence implies that the use of internet banking is ongoing.