Which of the following statements correctly explains the cause of this observed motion?
Convection currents within the air chamber generated by local heating from the microscope's light source.
The continuous, random bombardment of the soot particles by much smaller, rapidly moving air molecules, causing a fluctuating net force.
Microscopic electrostatic forces of repulsion and attraction between individual soot particles.
High-frequency acoustic vibrations in the air chamber caused by the microscope's cooling fan.
