Observe the following. \[\begin{align} & \mathbf{1\times \_\_=30} \\ & \mathbf{2\times \_\_=30} \\ & \mathbf{3\times \_\_=30} \\ & \mathbf{5\times \_\_=30} \\ \end{align}\] What is the sum of all the missing factors of 30?

• A.  60                              
• B.  30                  
• C.    45                  
• D.    61