Find an Algebraic Expression Equivalent To $\sec \left(\tan ^{-1} x\right)$ A) $\sqrt{x^{2}+1}$

Multiple Choice

Find an algebraic expression equivalent to $\sec \left(\tan ^{-1} x\right)$

A) $\sqrt{x^{2}+1}$
B) $\frac{1}{\sqrt{x^{2}+1}}$
C) $\frac{\sqrt{x^{2}+1}}{x}$
D) $\sqrt{x^{2}-1}$
E) $x^{2}+1$