Shift Function Up or Down: f(x)+c

The following table shows the inputs and outputs for the function $f(x)$. Which of the following functions are vertical shifts of $f(x)$?

$$\begin{array}{|l|l|} \hline x&0&1&2&3&4&5&6&7&8&9\\ \hline f(x)&2&4&6&8&10&12&14&16&18&20\\ \hline \end{array}$$