A. Create a firewall rule; select the correct network and select the target as all instances in the network and specify the custom port and protocol.

B. Create a firewall rule; select the correct network , create a target tag and attach the tag to the compute engine instance and allow traffic to custom port that is mapped with Jenkins.

C. Create a firewall rule; select the correct subnet which has the compute engine and allow all protocols and ports .

D. Create a firewall rule; select the correct subnet , create a target tag attach it to the compute engine instance and allow all protocols and ports.