To simplify the expression \( 425.82 - (-120.75) \), we can first convert the subtraction of a negative number into addition:
\[ 425.82 - (-120.75) = 425.82 + 120.75 \]
Next, we perform the addition:
\[ 425.82 + 120.75 = 546.57 \]
Therefore, the simplified result is \( 546.57 \).
The correct answer is: D 546.57