Beartrice purchased an enomous pie weighing $2.5\textasciitilde kg$. She gave $\frac{3}{13}$ of her pie to her friend Platilocks. She cut the remainder equally into $5$ slices. What fraction of the whole cake was each slice? 
选项为:A:$\frac{3}{10}$  B:$\frac{2}{13}$  C:$\frac{5}{13}$  D:$\frac{1}{5}$  请回答其中一个选项.