Stream of consciousness is a writing technique in which: a.the writer s thoughts

A. The writer's thoughts float from topic to topic..

The 'to' is part of the infinitive verb form. It is not a preposition.

Explanation:

Remember this:

If a verb follows the word 'to,' then it is an infinitive. If the word that follows the word 'to' is an article, a pronoun, or a noun, then the 'to' is a preposition.

        prep.             infinitive

I went to  the store to buy  a car.