Explanation
The option that would tell OpenVPN to use a dynamic source port when making a connection to a peer is nobind. This option instructs OpenVPN to not bind to a specific local port number, but instead use an ephemeral port number chosen by the operating system. This allows multiple OpenVPN instances to connect to the same remote server or peer without port conflicts. The other options are either invalid or have different meanings:
src-port: This is not a valid OpenVPN option and will cause an error.
remote: This option specifies the host name or IP address and port number of the remote server or peer to connect to. It does not affect the source port of the client.
source-port: This is not a valid OpenVPN option and will cause an error.
dynamic-bind: This is not a valid OpenVPN option and will cause an error.
References: LPIC-2 202 exam objectives, LPIC-2 202-450 Exam Prep: Network Configuration, Reference Manual For OpenVPN 2.4