What factors can change trade discount rates?

what factors can change trade discount rates?
Im wondering the same thing! I got nothing though. I just posted that too! Maybe we can help each other. Need it by tomorrow night.

Dear nblair22 I need it by tomorrow also any ideas

The single equivalent discount rate of the trade discount 5/4/1 is: (Points : 2)
.09712
.90288
.00002
.99998
None of these