单选题 Mark's Warehouse Clearance Store is having a sale with savings of up to 40 percent off on all clothing this weekend ______ celebration of its 25th anniversary.
A. in B. at C. on D. of

【正确答案】 A
【答案解析】[解析] 本题需选择常用词组中的介词，“纪念……的”表达方式是in celebration of...。