A) The zeroth law of thermodynamics leads to the concept of temperature.
B) The first law of thermodynamics is the general law of conservation of energy applied to any system in which energy transfer from or to the surroundings (through heat and work) is taken into account.
C) A quasi-static process is an infinitely slow process such that the system remains in thermal and mechanical equilibrium with the surroundings throughout.
D) Spontaneous processes of nature are irreversible.