If you need to make the ECS instances under three VSwitches (inside the same Alibaba...

Create three Security Groups, each containing all ECS instances under these three VSwitches. First, configure each Security Group to allow access to all CIDR Blocks. Then, configure each Security Group to forbid access to the CIDR blocks of the other two VSwitches (with this rule given higher priority than the previous rule).

Create three Security Groups, each containing all ECS instances under these three VSwitches. First, configure each Security Group to allow access to all CIDR Blocks. Then, configure each Security Group to forbid access to the CIDR blocks of the other two VSwitches (with this rule given a lower priority than the previous rule).

Create one Security Group containing all ECS instances under these three VSwitches. First, configure the Security Group to allow access to all CIDR Blocks. Then, configure the Security Group to forbid access to the CIDR blocks of the other two VSwitches (with this rule given higher priority than the previous rule).

None of these answers are correct.