Consider the Following Actions Undertaken by a Firm

Consider the following actions undertaken by a firm:
a) charging the same price for products of different quality
b) charging different prices to different consumers for the same product when the variation cannot be explained by cost differences
c) charging different prices for products of different qualities
d) charging a lower price to match a competitor's price
Which of the above will be considered price discrimination?

A) a, b, and d only
B) b and d only
C) a and b only
D) a, b, c, and d