Final answer:
Lennie becomes furious and blames the puppy for its own death, showing his inability to comprehend the situation.
Step-by-step explanation:
Lennie's irrational anger when he does not understand about the puppy's death is described in option a) Lennie becomes furious and blames the puppy for its own death, showing his inability to comprehend the situation. In the passages provided, Lennie's anger is evident when he fails to grasp why the puppy died. He is unable to understand that his own strength caused the puppy's death and instead directs his anger towards the puppy itself.