Which of the following is true:

Physical contact is necessary for the conduction of heat between the two objects.

There are 3 types of heat transfer

1. Conductive heat transfer:- Direct contact with each other. Mostly occurs in molecules which have less space between them. Medium is required
2. Convective heat transfer:- Mostly through the air. Medium required.
3. Radiation heat transfer:-  No medium required. Can occur in a vacuum also.