​Retailers often do not find it profitable to engage in promotional activities because

A) ​They cannot reap the full benefits of the promotion
B) They have to share the benefits of the promotion with the manufacturer
C) They are wary of competing retailers' ability to "free ride" on their efforts
D) ​All of the above

Retailers often do not find it profitable to engage in promotional activities because they cannot reap the full benefits of the promotion, as they have to share the benefits of the promotion with the manufacturer. Additionally, they are wary of competing retailers' ability to "free ride" on their efforts. Therefore, all of the above reasons contribute to retailers' reluctance to engage in promotional activities.