Final answer:
In the given sentence, 'soon' is the adverb as it modifies the verb 'go,' indicating the timing of the action.Option A is correct answer.
Step-by-step explanation:
In the sentence 'Let's go to the store soon so we can get back before it rains!', the adverb in question is 'soon' (A). This is because it modifies the verb 'go,' indicating the time frame in which the action should take place. Adverbs typically modify verbs, adjectives, or other adverbs, providing information about manner, time, place, or degree. In this case, 'soon' suggests that the activity of going to the store should happen in the near future.