Comparison between Load flow Methods

Q. If the reference bus is changed in two load flow runs with same system data and power obtained for reference bus taken as specified $P$ and $Q$ in the later run

1. the system losses will be unchanged but complex bus voltages will change.
2. the system losses will change but complex bus voltages remain unchanged.
3. the system losses as well as complex bus voltage will change.
4. the system losses as well as complex bus voltage will be unchanged.

Q. In load flow analysis, the load connected at a bus is represented as

1. constant current drawn from the bus
2. constant impedance connected at the bus
3. voltage and frequency dependent source at the bus
4. constant real and reactive power drawn from the bus