$\underline{\textbf{Answer:}\Rightarrow}\mathbf{B)\;5}$
$\underline{\textbf{Explanation:}\Rightarrow}$
$\underline{\text{Step:1}}$
$\mathrm{x = 1,\;i = 1}$
$\underline{\text{Step:2}}$
$\mathrm{x = 2,\;i = 2}$
$\underline{\text{Step:3}}$
$\mathrm{x = 4,\;i = 3}$
$\underline{\text{Step:4}}$
$\mathrm{x = 16,\;i = 4}$
Now, $\mathrm{x = 16}\le500$
$\underline{\text{Step:5}}$
$\mathrm{x = 2^{16},\;i = 5}$
$\therefore \;\mathbf 5$ is the right answer.