Which of the following is NOT prohibited by the Robinson-Patman Act?

The correct choice indicates that offering discounts to loyal customers is not prohibited by the Robinson-Patman Act. This Act primarily addresses price discrimination, which occurs when a seller charges different prices to different buyers for goods of similar quality, and it aims to prevent unfair competition that harms competitors or consumers.

Discounts to loyal customers are generally considered a legitimate business practice. Businesses often implement loyalty programs to reward customers for repeat purchases, which can enhance customer retention and satisfaction without violating the principles of fair competition outlined in the Act. This type of discounting is viewed as a value-addition for customers rather than an unfair advantage over competitors.

In contrast, practices like colluding with competitors or charging different prices to consumers without justification or notice of product differences are directly related to anti-competitive behavior, which the Robinson-Patman Act is designed to combat. Similarly, offering special prices to certain groups can raise issues under the Act if it leads to unfair competition. Thus, the allowed practice of discounting for loyalty is distinct from the prohibitions outlined in the Act.