Final answer:
Jem is trying to temporarily store away the traumatic memories of the trial to deal with them later, matching the second option provided.
Step-by-step explanation:
After witnessing the disheartening outcome of the trial in To Kill a Mockingbird, Jem is attempting to cope with his disillusionment. According to Atticus's observation, what Jem is trying to do is store the memories away temporarily. He is not yet ready to fully process the traumatic experience, so his actions align with the second option. Jem's reaction reflects a common psychological response where individuals may temporarily put away difficult memories in order to deal with them at a later time when they might be more prepared to handle the emotional impact.