When 68-year-old Mrs. Blake had a flat tire on a fairly isolated highway, she received help from a passerby in less than 10 minutes. One year later, she had a flat tire on a busy freeway and an hour elapsed before someone finally stopped to offer assistance. Mrs. Blake's experience best illustrates
a. the fundamental attribution error.
b. the mere exposure effect.
c. group polarization.
d. the bystander effect.
Answer: d