It's September and Sophia Wants to Buy Some Arts and Crafts

It's September and Sophia wants to buy some arts and crafts supplies for an after-school program she is developing for her daughter's elementary school.In her Saturday newspaper was a flyer from Michael's,an arts and crafts retailer.As she looked through the newspaper insert,she noticed that if she purchased three or more bottles of Alene's Tacky Glue,the regular price of $1.50 each was reduced to $1.15 each.She also saw that the store priced its plastic storage boxes at $1.99,$3.99,and $5.99.She thought they would be useful for storing each individual child's projects.On the front page of the flyer was an ad for Funky Girls Gel Pens,something she knew her daughter would love to use.The price at Michael's was $6.99 lower than the price she had found at the other stores that carried the pens.She thought that some of the older girls might like to start a scrapbook and was pleased to find that Michael's had a scrapbook starter kit,which includes scissors,book,pages,and stickers for only $15.The items could be purchased separately for $19.99.The flyer also announced that all flag-related items left over from its Canada Day sale were reduced by 40 percent.
-Refer to Art Supplies.What pricing practice was used to price the plastic storage boxes?

A) seasonal pricing
B) price shading
C) price lining
D) cumulative pricing