It shows that older people often ignore or minimize children's feelings
This means that he feels very drugged as if he had just taken an opioid or something. He hears a nightingale singing saying that the bird is spreading its happiness too much. He is also saying that he too is happy because he can hear the nightingale sing somewhere amidst the forest.
The Correct Answer Is A: Don't Run Into Any Of The Following: A Tree, A Mailbox, Or A Lamp Post. Hope I Helped