Step 1: Use the relation between Celsius and Fahrenheit scales.
The relation is
\[
F=\frac95C+32.
\]
According to the question,
\[
F=C+80.
\]
Step 2: Equate the two expressions.
Substituting,
\[
\frac95C+32=C+80.
\]
Rearranging,
\[
\frac45C=48.
\]
Hence,
\[
C=48\times\frac54=60.
\]
Therefore,
\[
F=60+80=140.
\]
Thus, the temperature is
\[
\boxed{60^\circ\text{C}}
\]
(or equivalently \(140^\circ\text{F}\)).
Hence, the correct option is \(\boxed{(D)}\).