I don’t see the passage but it is probably struggle.
The answer It’s either A or B the rest DONT add up
It's not likely you'll overdose on nicotine just from smoking cigarettes. Your body absorbs the nicotine in a cigarette around 1 milligram when you smoke it. Overdosing from nicotine gum or a patch is rare but it's possible if you don't follow the instructions carefully.
Its saying basically that there are hidden secrets underneath people. That every smile, nod or wave has a hidden agenda. It's like warning to be wary of who you trust.
The answer is B. exposition, the exposition gives info on the story and background characters before the plot takes place.