It is four months since I last saw Keats ______.

It is four months since I last saw Keats ______.
a.at Mrt Smith’s ,the book seller c.at my aunt’s,a book seller
b.at my aunt’s,Mrs Palmer’s d.at Mrs Palmer’s,the book seller’s
请高手给个确切的答案,讲下其中的语法知识,

首先排除B和D,意义上不通顺 C的问题出在冠词a上 逗号前指的是一个地方 逗号后是对这个地方所有者身份的解释 故是特指 用冠词the 而不是a
答案选A