Answer: The option that best represents the simple predicate of the sentence provided is "walks".
Step-by-step explanation: The simple predicate of a sentence is main the verb or verb phrase which indicates the action that the subject is performing or the process that it is going through. In that way, the simple predicate includes only the verb, that is to say it does not include its modifiers. In the sentence "The girl in the blue dress walks to church", the simple predicate is "walks" because it is the only verb in the sentence and, at the same time, it is expressing the action that "the girl in the blue dress" is carrying out.