Answer
$\textbf{I}$
Work Step by Step
Recall: $\sec\theta=\frac{1}{\cos\theta}$
Using degree mode and cosine function, we can find $\cos18^{\circ}$ and then its inverse to get $\sec18^{\circ}$.
$\sec 18^{\circ}=\frac{1}{\cos 18^{\circ}}\approx1.051462224$
The appropriate approximation is $\textbf{I}$.
