The initial concentrations of +and -in the reaction below are each 0.0892. If the initial concentration of NaCl is 0 and the equilibrium constant is Kc=8.21 under certain conditions, what is the equilibrium concentration of +?
NaCl()⇌+()+-()
Select the correct answer below:

a. 0.0883
b. 0.0751
c. 0.0253
d. 7.84×10⁻⁴