Which of the following Boolean expressions is not a tautology?

$\displaystyle (p \Rightarrow q) \vee(\sim q \Rightarrow p)$

$\displaystyle (\mathrm{p} \Rightarrow \sim \mathrm{q}) \vee(\sim \mathrm{q} \Rightarrow \mathrm{p})$

$\displaystyle (\sim \mathrm{p} \Rightarrow \mathrm{q}) \vee(\sim \mathrm{q} \Rightarrow \mathrm{p})$

$\displaystyle (\mathrm{q} \Rightarrow \mathrm{p}) \vee(\sim \mathrm{q} \Rightarrow \mathrm{p})$