#### Answer

$C$

#### Work Step by Step

The tangent and secant functions are not defined for the following angles (or values of s):
$\frac{\pi}{2}, \frac{3\pi}{2}, \frac{5\pi}{2}, \frac{7\pi}{2},...$
Notice that the values above have numerators whose coefficient of $\pi$ is an odd number.
In the expression $(2n+1)\frac{\pi}{2}$, the value of $(2n+1)$ is always an odd number for all values of $n$.
Thus, the domain of the tangent and the secant functions is $(2n+1)\frac{\pi}{2}$, where $n$ is any integer.