Final answer:
The incomplete sentence about Rodger throwing rocks lacks context to determine the correct object. References provided describe other beach activities but do not relate to Rodger's actions. Without additional information, we cannot accurately fill in the blank.
Step-by-step explanation:
The student's question asks for a completion of a sentence describing Rodger's actions at the beach. Rodger kicks over several sand castles and throws rocks at missing object. The sentence requires an object to be grammatically complete. However, the information provided does not specify what object Rodger throws rocks at, so without more context it is impossible to accurately fill in the blank.
The references provided describe two separate beach scenes. In one, a party, including Mr. Sieppe, checks their baskets and releases a greyhound as they head to the seashore. In the other scene, Ben and his son, Julian, are paddling out into the ocean on surfboards and attempting to ride a wave. Neither of these scenes gives us information about Rodger's actions or what he might be throwing rocks at.