Answer:
The correct answer is - these drugs inhibit both the polymerization and depolymerization of actin.
Step-by-step explanation:
Cytochalasin is a chemical drug that covers or hides the plus end of the actin filament which inhibits the binding of actin monomers and actin polymerization on another hand the Phalloidin chemical makes the actin filaments stable by attaching to them and inhibits the depolymerization process.
The addition of any of these drugs stops the cell movement which is caused by the actin polymerization and depolymerization which is stoped by these drugs. Cell movement is the process that required both actin polymerization and depolymerization.