Decide Whether the Equation Is Conditional, an Identity, or a Contradiction

Multiple Choice

Decide whether the equation is conditional, an identity, or a contradiction. Give the solution set.
- $5(2 \mathrm{f}-31) =10 \mathrm{f}-155$

A) Conditional; $\{0\}$
B) Contradiction; $\varnothing$
C) Identity; {all real numbers}
D) Identity; $\varnothing$