One brand of milling machine has the following two index plates supplied along with the indexing head:
Plate 1: $$15, 16, 17, 18, 19, 20$$ hole circles.
Plate 2: $$21, 23, 27, 29, 31, 33$$ hole circles.

It is proposed to mill a spur gear of $$28$$ teeth using simple indexing method. Which one of the following combinations of index plate and number of revolutions is correct?

Match List - $${\rm I}$$ (Milling problem) with List - $${\rm I}$$$${\rm I}$$ (Probable causes) and select the correct answer using the codes given below the lists:

Match List - $${\rm I}$$ (Cutting tools) with List - $${\rm I}$$$${\rm I}$$ (Features) and select the correct answer using the codes given below the lists:

$$NC$$ contouring is an example of