In postgresql.conf you can set various parameters that control the operation of the server. Many parameters are changed by reloading the file with pg_ctl reload, but some parameter change requires restarting the server such as pg_ctl restart.

Of the parameters discussed in the example, changing the port (the port number monitored by the server) and max_connections (the maximum number of simultaneous connections to the server) requires restarting the server.

log_connections (setting whether to keep client connection attempts in the log) or log_line_ prefix (output format of logs) change more than just reload.

If search_path (the default schema search path) also changes its setting, the new setting become effective for subsequent client connections.

Therefore, the correct answers are A and B.