Two regional systems, each having several synchr onous generators

Two regional systems, each having several synchr onous generators and loads are interconnected by an ac line and a HVDC link as shown in the figure given below. Which of the following statements is true in the steady state?

1. Both regions need not have the same frequency
2. The total power flow between the regions (P_ac + P_dc) can be changed by controlling the HVDC converters alone
3. The power sharing between the ac line and the HVDC link can be changed by controlling the HVDC converters alone.
4. The direction of power flow in the HVDC link (P_dc) cannot be reversed

By changing the grid angle, we can change the power sharing between the AC line and HVDC link.