question: What is the main difference between the LQR (Linear Quadratic Regulator) control and the LQG (Linear Quadratic Gaussian) control? option 1: LQR assumes no noise and full state observation, while LQG considers input and measurement noise and partial state observation. option 2: LQR considers input and measurement noise and partial state observation, while LQG assumes no noise and full state observation. option 3: LQR and LQG are the same controller design but for different types of systems. option 4: LQR is designed for linear systems, while LQG is designed for nonlinear systems. option 5: LQR and LQG are both designed for linear systems but with different optimization objectives. 