Occurs when heat is transferred to an object through direct contact with particles; an example would be the heat from a stove transferring to your hand through the handle on a pot or pan.
a. conduction
c. convection
b. radiation
d. heat

The answer is conduction. There are three mechanisms of heat transference: conduction, convection and radiation. Conduction is the transference of heat between layers (particles) in direct contact; it is due to the vibration of the atoms that form the substances. Convection takes place in fluids (gases and liquids) and is due to the translation (motion) of the fluid, this is hot masses of the fluid translate and replaces cold masses. Radiation is the transmission of heat due to electromagnetic waves and do not require a medium (conduction and convection transfers through a medium): the Sun heats the Earth by radiation.

Some type of thing that was invisible

The best description is: . nobody has any idea what q is.