In the Problem, T Is a Real Number and P $\left( - \frac { \sqrt { 21 } } { 5 } , - \frac { 2 } { 5 } \right)$

In the problem, t is a real number and P = (x, y) is the point on the unit circle that corresponds to t. Find the exact value of
the indicated trigonometric function of t.
- $\left( - \frac { \sqrt { 21 } } { 5 } , - \frac { 2 } { 5 } \right)$ Find cot $t$

A) $- \frac { \sqrt { 21 } } { 2 }$
B) $\frac { \sqrt { 21 } } { 2 }$
C) $- \frac { 2 \sqrt { 21 } } { 21 }$
D) $\frac { \sqrt { 21 } } { 5 }$