The total nodal delay is the total sum of propagation, transmission and processing delay in a particular network. If a packet are transmitted from one node to another node in the network, then the packet suffers from various type of delay in the network.
Propagation delay is the amount of time that is taken by the device from the sender to the receiver along with the signal header.
Transmission delay is the total time that is required for pushing the bits present in the packets on the wire/link.
Processing delay is the time taken by the router to process in the packet header and it is the key component of the network delay.
D. Prototyping. This is because a prototype is basically a replica of the original one and in order to find out what all we need to add in our original, material selection plays a vital role in prototypes.