Final answer:
Without specific context from the text involving Zachary Beaver, the reason for him pressing his arms against his sides cannot be determined. The provided reference about C.J. does not directly relate to this character's behavior.
Step-by-step explanation:
The question "Why does Zachary Beaver press his arms against his sides?" provides several options to consider. However, without specific context from the text or book in which Zachary Beaver is a character, it's not possible to determine the correct answer with certainty. In literature, characters may exhibit such behaviors for various reasons, including feeling cold, attempting to hide, having a medical condition, or out of habit. To accurately answer why Zachary Beaver does this, one would need to refer to the particular story where this behavior is described.
In the reference given, which discusses C.J. being stuck in her car during a blizzard, the reaction to extreme cold involves the body becoming lethargic to conserve heat, not necessarily pressing arms to the sides. Thus, without further context from Zachary Beaver's story, the answer cannot be confidently provided.