Which sentence contains a split infinitive?

a. young children seem to thoroughly enjoy playing with soap bubbles and shaving cream.
b. it is important to give children opportunities to explore their world through sensory experiences.
c. clay and finger paints are often used to prepare children for writing and drawing.
d. going to preschool opens the door to learning and encourages kindergarten readiness.

The answer to your question would be that the sentence that contains a split infinitive is the following one: Young children seem to thoroughly enjoy playing with soap bubbles and shaving cream. That is, the correct option would be A.

A split infinitive or cleft infinitive is a grammatical construction in which a word or phrase comes between the infinitive particle to and the bare infinitive of the to form of the infinitive verb. Usually, an adverb or adverbial phrase comes between them. In this case, it is the adverb "thoroughly".

Correct answer choice is :

In the English language, a split infinitive or cleft infinitive is a grammatical structure in which a word or phrase comes among them too and the easy infinitive of the to form of the infinitive verb. Normally, an adverb or adverbial phrase comes between them.

a. it reminds protestors of the reasons they have to protest.