Select the sentence with the appropriate use of preposition.

Children are fond of sweets.

The sentence with the appropriate use of preposition is Children are fond of sweets.

The preposition "of" is used to indicate a liking or fondness for something. In this case, the speaker is saying that children like sweets.

The other prepositions in the options are not appropriate for this sentence. The preposition "to" is used to indicate direction or movement. The preposition "off" is used to indicate distance or separation. The preposition "with" is used to indicate association or accompaniment.