Final answer:
The preposition in the sentence 'Erin wandered into the pet store' is 'into'.
Step-by-step explanation:
The preposition in the sentence 'Erin wandered into the pet store' is into. A preposition is a word that shows a relationship between a noun (or pronoun) and another word in the sentence. In this case, 'into' shows the relationship between 'Erin' and 'the pet store'.
Learn more about prepositions