Use the Properties of the Trigonometric Functions to Find the Exact

Use the properties of the trigonometric functions to find the exact value of the expression. Do not use a calculator.
- $\sec ^ { 2 } 40 ^ { \circ } - \tan ^ { 2 } 40 ^ { \circ }$

A) 0
B) 2
C) 1
D) -1