Select the correct passive form of the given sentence.

She has put fresh flowers in the flower vase.

Fresh flowers have been put in the flower vase.

The correct passive form of the given sentence "She has put fresh flowers in the flower vase" is Fresh flowers have been put in the flower vase.

The other options are incorrect because:

• Fresh flowers are put in the flower vase uses the present simple tense, while the original sentence is in the present perfect tense.
• Fresh flowers are being put in the flower vase uses the present progressive tense, which is not typically used for actions that happen once.
• Fresh flowers has been put in the flower vase uses the singular form of the verb "to be" for a plural subject, which is grammatically incorrect.