A reaction A(g) ⇌ B(g) has an equilibrium constant of 1.0 * 10^-4. For which of the initial reaction mixtures is the x is small approximation most likely to apply?

a. [A] = 0.0010 M; [B] = 0.00 M

b. [A] = 0.00 M; [B] = 0.10 M

c. [A] = 0.10 M; [B] = 0.10 M

d. [A] = 0.10 M; [B] = 0.00 M