Which statement about MTU and PMTU is correct? (Multiple Choice)

Which statement about MTU and PMTU is correct? (Multiple Choice)
A . MTU (Maximum Transfer Unit) refers to the size of the largest data packet that can be transmitted in the network, in bytes.
B. The device will check the MTU on the inbound interface, and if the packet size exceeds the MTU value, it will be discarded.
C. In an IP network, interfaces with different MTU values may be passed from the source address to the destination address, and the largest MTU value is the PMTU of the path.
D. PMTU detection is to obtain the PMTU value of the specified destination IPv4 address through detection, and then use the MTU value to send packets.

Answer: AD