The correct answer is: Bidirectional port.
A bidirectional port is a port that can transmit and receive data. This is important in a multi-master system, where multiple devices are trying to access the same data. If the ports were unidirectional, only one device would be able to access the data at a time, which could lead to errors.
A tridirectional port is a port that can transmit, receive, and send data. This is not necessary in a multi-master system, as the devices can communicate with each other without the need for a third party.
A multi-directional port is a port that can transmit, receive, and send data in multiple directions. This is not necessary in a multi-master system, as the devices can communicate with each other in a single direction.
A unidirectional port is a port that can only transmit data. This is not ideal in a multi-master system, as it would prevent the devices from communicating with each other.