i want to ask that is it a, b, c or d?

Jennifer Merryman keeps pace with her teenage sons, who occasionally visit porn sites, by installing a monitoring program that allows her to see every Web site they visit and every e-mail they send and receive. "I consider myself a strict and hip mom, so I talk to them about porn," she says. "I told them, 'I can watch anything you are doing on the computer. If you see something you don't want your mom to see, don't go there.'& quot;
According to paragraph four, how does Richardson know to ignore messages from strangers?
answer:
A.Because her parents strictly monitor what she does online.

a......