Select the correct statement(s) regarding Frame Relay (FR).a. FR is a connection-oriented standard that operates at the OSI layers 1 and 2b. FR packets are fixed length, therefore transmission delays are predictablec. FR operates at the OSI RM network layer 3 to ensure end-to-end connectivity over wide areasd. all of the statements are correctAnswer: a. FR is a connection-oriented standard that operates at the OSI layers 1 and 2