When designing a WAN that will be carrying real-time traffic, what are two important reasons...

Serialization delays are invariable because they depend only on the line rate of the interface.

Serialization delays are variable because they depend on the line rate of the interface and on the type of the packet being serialized.

Serialization delay is the time required to transmit the packet on the physical media.

Serialization delays are variable because they depend only on the size of the packet being serialized.

Serialization delay depends not only on the line rate of the interface but also on the size of the packet.