Two sets of numbers are given. The second set of numbers is obtained by doing something to the first set.  $\left\textbackslash{ 1,2,3,4,5\right\textbackslash}\textbackslash{} \Rightarrow\left\textbackslash{ 2,5,10,?,26\right\textbackslash}$  What is the missing number? 
选项为:A:$$12$$  B:$$17$$  C:$$21$$  D:$$37$$  E:$$50$$  请回答其中一个选项.