INCORRECT!
Guardrail is the preferred method of fall protection as it provides a physical barrier for multiple operators to work behind safely. This form of protection is ideal for frequently accessed areas.
Walkways are not classed as fall protection, they are a means of access for the operator to move around the roof.
Anchors are an active means of fall protection requiring the operator to use a harness and lanyard and therefore need a higher level of user competence. This means of fall protection would be used for periodic maintenance tasks.