The insertion box below has three plug compartments (red, yellow and blue). There are short circuits between the pair of terminals at the side of each compartment. These short circuits allow the line currents to flow through the insertion box to the three phase load. When the plug of the insertion box is inserted into a compartment the short circuit corresponding to that compartment is replaced by whatever circuitry is connected across the black terminals. 

Please state which of the following statements are TRUE.

1. If the plug is inserted into the red compartment, the circuit across the black terminals is inserted into the red phase.  

2. If the plug is inserted into the yellow compartment, the circuit across the black terminals is inserted into the yellow phase.  

3. If the plug is inserted into the blue compartment, the circuit across the black terminals is inserted into the blue phase.

4. If the plug is inserted into any of the compartments and there is nothing connected across the black terminals, it will insert an open circuit into the line associated with that plug compartment.