$A=45^{\circ}, B=30^{\circ}$ হলে $\sec (\mathbf{B}-\mathbf{A})$ এর মান কত?

$\frac{\sqrt{3}+1}{2 \sqrt{2}}$

$-\frac{\sqrt{3}+1}{2 \sqrt{2}}$

$\frac{2 \sqrt{2}}{\sqrt{3}+1}$

$-\frac{2 \sqrt{2}}{\sqrt{3}+1}$