Use Periodic Properties of the Trigonometric Functions to Find the Exact

Multiple Choice

Use periodic properties of the trigonometric functions to find the exact value of the expression.
- $\tan \frac { 21 \pi } { 4 }$

A) 1
B) $\sqrt { 3 }$
C) $\frac { \sqrt { 3 } } { 3 }$
D) $- 1$