Rewrite the Expression in Terms of Exponentials and Simplify the Results

Multiple Choice

Rewrite the expression in terms of exponentials and simplify the results.
- $( \sinh 10 x - \cosh 10 x ) ^ { 4 }$

A) $e ^ { 40 x } - e ^ { - 40 x }$
B) $e ^ { - 40 x }$
C) $- \mathrm { e } ^ { - 40 x }$
D) $e ^ { - 10 x ^ { 4 } }$