Question

which is required for conduction?
two substances in close proximity, but not necessarily touching
moving fluids
two substances in direct contact with one another

Explanation:

Conduction is the transfer of heat through direct contact between two substances. For conduction to occur, the two substances must be in direct contact with one another. If they are just in close proximity but not touching (as in the first option), heat transfer by conduction won't happen effectively. Moving fluids (the second option) is related to convection, not conduction.

Answer:

Two substances in direct contact with one another