The Mathematical Expression for the Change in Free Energy of a System

The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is correct?

A) ΔS is the change in enthalpy, a measure of randomness.
B) ΔH is the change in entropy, the energy available to do work.
C) ΔG is the change in free energy.
D) T is the temperature in degrees Celsius.