This branch of physics evolved out of a goal to increase the efficiency of steam engines, through the work of scientists like Sadi Carnot and Lord Kelvin. This branch of physics is governed by four laws, the third of which states that the entropy of a perfect crystal approaches zero as the temperature approaches zero. The First Law of this branch describes the change in a system's internal energy in accordance with the Law of Conservation of Energy. For 10 points, name this branch of physics concerned with heat and temperature and its relation to energy and work.
a) Thermodynamics
b) Quantum mechanics
c) Electrodynamics
d) Astrophysics