Select the subject of the sentence.

During the blackout, the fourth graders told scary stories in Eugene Krabs's tree house.

fourth graders

The subject of the sentence is "the fourth graders."

To determine the subject of the sentence, we need to identify who or what is performing the action in the sentence. In this case, the action is the telling of scary stories. The subject will be the noun or pronoun that is performing this action.

Let's break down the sentence:

During the blackout - This is a prepositional phrase that provides additional information about when the action occurred.

the fourth graders - This is the noun phrase that is the subject of the sentence. It refers to a group of individuals, specifically students in the fourth grade.

told - This is the verb, indicating the action of telling.

scary stories - This is the object of the verb, specifying what the fourth graders told.

in Eugene Krabs's tree house - This is another prepositional phrase that provides additional information about where the action took place.

Based on this analysis, the subject of the sentence is "the fourth graders."