An idealised atom has a non-degenerate ground state at zero energy and a g-fold degenerate excited state of energy E. In a non-interacting system of N such atoms, the population of the E excited state may exceed that of the ground state above a temperature T> The 2k, In 2 minimum value of g for which this is possible is (a) 8 (b) 4 (c) 2 (d) 1