Which Statement Below Regarding the Equilibrium Constant and Its Units

Which statement below regarding the equilibrium constant and its units is true?

A) K is unitless because the concentrations or partial pressures in the expression are theoretically ratios of concentration or partial pressure to an ideal value of 1.000 M or 1.000 atm.
B) K is unitless because the units of the concentrations or partial pressures in the expression are dropped for convenience.
C) K is unitless because the units of the concentrations or partial pressures in the expression cancel if the equilibrium expression is written correctly.
D) K has units that reflect the units of the concentrations or partial pressures in the equilibrium expression.
E) K has units of M or atm, depending on whether solutions or gases are involved.