To solve the expression \( -99.85 - 16.98 \), you can combine the two negative numbers:
\[ -99.85 - 16.98 = - (99.85 + 16.98) \]
Now, add \( 99.85 \) and \( 16.98 \):
\[ 99.85 + 16.98 = 116.83 \]
Therefore,
\[ -99.85 - 16.98 = -116.83 \]
The correct answer is \( -116.83 \).