Introduction:
UDP (User Datagram Protocol) is a connectionless transport protocol that operates on the transport layer of the TCP/IP protocol stack. UDP does not provide congestion control mechanisms, making it unsuitable for applications that require reliable and ordered delivery of data. However, there is a version of UDP that incorporates congestion control called Datagram Congestion Control Protocol (DCCP).

Datagram Congestion Control Protocol (DCCP):
DCCP is a transport protocol that provides congestion control for applications that use datagrams. It is designed to be flexible, allowing applications to specify their own congestion control mechanisms. DCCP uses a congestion control scheme called TCP-like congestion control, which is similar to the congestion control mechanism used in TCP.

Stream Control Transmission Protocol (SCTP):
SCTP is another transport protocol that provides congestion control. However, it is not a version of UDP. SCTP is a reliable transport protocol that offers features like multi-streaming, multi-homing, and message-oriented communication. It is designed to provide reliable and ordered delivery of data with congestion control.

Structured Stream Transport (SST):
SST is not a version of UDP with congestion control. It is a research project that aims to develop a transport protocol that provides reliable and ordered delivery of data with congestion control. SST is designed to be highly scalable and efficient, making it suitable for high-performance computing environments.

Conclusion:
Among the given options, the version of UDP with congestion control is Datagram Congestion Control Protocol (DCCP). DCCP provides congestion control mechanisms for applications that require reliable and ordered delivery of datagrams. Stream Control Transmission Protocol (SCTP) is another transport protocol that provides congestion control, but it is not a version of UDP. Structured Stream Transport (SST) is a research project and not a version of UDP with congestion control.