VERY URGENT - 100 points

Fill in the blank -
One end of a rod is heated. The atoms at this end of the rod start to vibrate more energetically. These atoms collide with nearby atoms, and energy passes from the hotter to cooler atoms. As you are holding the rod in your hand, you feel the heat from the end that is being warmed move to the cooler end of the rod. This process of the heat being conducted through the rod is measured as the rod's (blank)

The options are :
Thermal emissivity
Thermal expansivity
Thermal reflectivity
Thermal conductivity

just give a simple answer PLS