Can someone explain this paragraph to me?

Don't eat the mushroom its poisonous

Realism was a fairly influential and widespread literary movement in the united states in the latter half of the nineteenth century. which american writer is among the pioneers of american realism? a. ernest hemingway b. f. scott fitzgerald c. j. d. salinger d. mark twain

Why is macbeth both excited and fearful after hearing the witches prediction about his future