Solid Z dissolves non-spontaneously below 280 K but dissolves spontaneously above 310 K, and its ΔH° is temperature-independent. Which set of thermodynamic conditions is most consistent with this behavior?
a) ΔH∘>0 and ΔS∘>0, with ΔS∘ΔH∘<280K
b) ΔH∘>0 and ΔS∘>0, with ΔS∘ΔH∘ between 280K and 310K
c) ΔH∘<0 and ΔS∘<0, with ΔS∘ΔH∘ between 280K and 310K
d) ΔH∘>0 and ΔS∘<0, regardless of magnitude