Which of the following phenomena constitutes a component of axonal transport?

Which of the following phenomena constitutes a component of axonal transport? (Points : 0.4)
Anterograde and retrograde axonal transport allow for the communication of nerve impulses between a neuron and the central nervous system (CNS).
Materials can be transported to the nerve terminal by either fast or slow components.
The unidirectional nature of the axonal transport system protects the CNS against potential pathogens.
Axonal transport facilitates the movement of electrical impulses but precludes the transport of molecular materials.