Answer
$S = 1.516 \times 10^{-23} J/K$
Work Step by Step
The equation of entropy in statistical thermodynamics is
$S = k\space ln W$
Taking W from (c) in system A that has the greatest multiplicity, we can find the greatest entropy in the system. And K is the Boltzmann's constant $k = 1.38 \times 10^{-23}J/K$
$S = (1.38 \times 10^{-23}J/K) \space ln 3$
$S = 1.516 \times 10^{-23} J/K$
