Hierarchical level control involves :
(a) Level 1: Actuator control controls individual robot actuators
(b) Level 2: Path control coordinates robot path movement
(c) Level 3: Main control high level instruction interpreter
(d) All of the mentioned
The question was posed to me in an interview for internship.
Asked question is from Robotic Control System in chapter Time Response Analysis, Design Specifications and Performance Indices of Control Systems