The correct choice is Option C: all three statements are true.
Here's why:
Equilibrium requires a closed system at constant temperature
If the system isn't closed, reactants or products can escape and you never reach a true dynamic balance.
And since the equilibrium constant depends on temperature, "at a given temperature" ensures K stays fixed.
All macroscopic (measurable) properties remain constant at equilibrium
Even though the forward and reverse reactions continue at the molecular level, their rates are equal, so pressure, concentration, temperature, etc., no longer change.
The equilibrium constant for the reverse reaction is the reciprocal of that for the forward reaction
If for
A⇌Bwe have
Kfwd=‌,then for the reverse
‌B⇌A,‌Krev=‌=‌.