b
(b) As we know, Rate of cooling $ \propto \frac{{\rm{1}}}{{{\rm{specific}}\;{\rm{heat(c)}}}}$
$\because {c_{{\rm{oil}}}} < {c_{{\rm{Water}}}}$
==> ${({\rm{Rate}}\;{\rm{of}}\;{\rm{cooling}})_{{\rm{oil}}}} > {({\rm{Rate}}\;{\rm{of}}\;{\rm{cooling}})_{{\rm{Water}}}}$
It is clear that, at a particular time after start cooling, temperature of oil will be less than that of water.
So graph $B$ represents the cooling curve of oil and $ A$ represents the cooling curve of water
