Question

melissa regularly donates blood to an international blood bank simply because she believes she ought to help anyone with a medical need for a blood transfusion. melissas altruism best illustrates the impact of the:
reciprocity norm.
social - responsibility norm.
mere exposure effect.
bystander effect.

Explanation:

• Reciprocity norm: This is about expecting a return favor. Melissa don't expect anything in return for her blood donation.
• Social - responsibility norm: It states that people should help those who need help. Melissa donates blood as she believes she should help those with medical need (which is in line with this norm).
• Mere exposure effect: It is about the increase in liking due to repeated exposure. Not relevant to altruism here.
• Bystander effect: It is about the decrease in likelihood of helping when there are more bystanders. Opposite of what Melissa is doing.

Answer:

social - responsibility norm.