Answer is: B. Heat transfers to his body from the water by conduction.
Thermal conductuction is the transfer of heat through physical contact. Thermal conduction is the transfer of heat by microscopic collisions of particles.
Heat spontaneously flows from a hotter (in this example water) to a colder body (in this example human body).
The process of heat conduction depends on four basic factors: the temperature gradient, the cross section of the materials involved, their path length and the properties of those materials.