Math Help (Again)? How would you draw a 0 degree angle?

I thought about drawing a line but that wouldn't make angle. An angle needs two rays right?
Update: I checked my notes and according to them 180 is not the right answer. It would be a straight angle not zero. I'm so going to fail my geometry test on Wednesday.
Update 2: About that infinitive line....
That wouldn't be an angle then if there's no vertex
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