Select the correct passive form of the given sentence.

The children sang the National Anthem with great enthusiasm

The National Anthem was sung with great enthusiasm by the children

The correct passive form of the given sentence is The National Anthem was sung with great enthusiasm by the children.

The active voice of the sentence is The children sang the National Anthem with great enthusiasm. This sentence is in the simple past tense, which is used to describe an action that happened in the past. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "the children" and the main verb is "sing." The past participle of "sing" is "sung." So, the passive form of the sentence is The National Anthem was sung with great enthusiasm by the children.

The other options are incorrect because:

• The National Anthem is sung with great enthusiasm by the children. is in the present tense, while the original sentence is in the simple past tense.
• The National Anthem has been sung with great enthusiasm by the children. is in the present perfect tense, which is used to describe an action that has happened in the past but is still relevant to the present. The action of singing the National Anthem is not something that is still relevant to the present.
• The National Anthem was being sung with great enthusiasm by the children. is in the past progressive tense, which is used to describe an action that was happening in the past but is not happening anymore. The action of singing the National Anthem is still happening in the present, so the past progressive tense is not the correct tense to use.