Select the most appropriate option to fill in the blank.

The writer declares that __________ children of their childhood is a criminal act.

robbing

The most appropriate option to fill in the blank is robbing.

The word "robbing" is a gerund, which is a verb that is used as a noun. In this case, the gerund "robbing" is used as the subject of the sentence. The sentence is saying that the writer declares that the act of robbing children of their childhood is a criminal act.

The other options are not as appropriate. The word "robbed" is the past tense of the verb "rob", and it would not make sense to say that the writer declares that children have been robbed of their childhood. The word "rob" is the infinitive form of the verb "rob", and it would not be grammatically correct to use it as the subject of the sentence. The word "to rob" is a prepositional phrase, and it would not be grammatically correct to use it as the subject of the sentence.