The correct option is B ZnS (Ksp=7×10−16)
Greater the value of s, greater is the solubility of the salt.
MnS(S)⇌Mn2+s(aq)+S2−s(aq)→Ksp=s2s=√Ksp=0.89×10−18 MZnS(s)⇌Zn2+s(aq)+S2−s(aq)→Ksp=s2s=√Ksp=2.64×10−8 MBi2S3(s)⇌2Bi3+2s(aq)+3S2−3s(aq)Ksp=22s2×33s3=108s5⇒s=(Ksp108)15=0.54×10−14MAg2S(s)⇌2Ag+2s(aq)+S2−s(aq)Ksp=4s3s=(Ksp4)13=1.14×10−17 M
Hence, ZnS is the most soluble.