Answer:
Faster particles bump into slower particles ( A )
Step-by-step explanation:
Thermal conduction in a solid involves the microscopic collision of particles in the solid and this particles are made up of electrons, molecules and atoms. the collisions occur when faster particles collide with slower particles and this happens in a disorganized manner.
when cannot say for sure in what direction each of the particles is moving but there is surely collisions between particles which in turn results to transfer of kinetic and potential energies