Anna owns a gallery. In order to attract people to attend her next show, she advertised in the newspaper that the first person to go in would have the opportunity to purchase a signed Andy Warhol poster for EUR200. Ben is an art collector and he would love to buy a signed Andy Warhol poster for EUR200. Ben decided to camp outside Anna’s gallery for two days. When the show opened, Ben was the first person to go in. Anna informed Ben that there were no Andy Warhol posters for sale at that show.Required:Advise Ben whether he has any cause of action against Anna. (5 marks)

水解后主要产生没食子酸和葡萄糖（或多元醇）的鞣质为（）。

A.没食子鞣质

B.逆没食子鞣质

C.咖啡鞣质

D.缩合鞣质

E.含有没食子酰基的缩合鞣质