Connect:Actively attempt to establish a connection so this system call is doing something so we can say that this is activeBind:Bind the IP address and port address to the SOCKET connection so this system call is doing something so we can say that this is activeListen:Shows the willingness to accept connections.Listen system call just makes the machine wait for someone to send a SYN packet so it simply convert unconnected socket to passive socketThis system call is waiting for SYN packet so this system call not doing something so passive.Accept:Block the caller until a connection attempts arrives, it does something so active.Hence listen is the correct answer.