After she received a free hand-painted Christmas ornament from a religious organization, Mrs. Montevecchi felt obligated to mail a cash donation to the organization. Her response to the free gift best illustrates the impact of the

Reciprocity norm

Explanation:

Reciprocity norm  is the principle that describes about repaying someone in the same manner in which they have favored us.This repayment is caused due to feeling of obligation. People expect benefit from doing favor for other person as response.

According to the question,reciprocity norm is displayed through scenario of Mrs. Montevecchi feeling obligated for returning favor to religious organization in form of donation because she got Christmas ornament from them as gift.  

it would be d). more resources must be obtained to attain that combination of goods and services