An angle is defined as two rays with a common endpoint, so CAB (or BAC) is an angle. A line is described as an infinite set of points that extend forever in either direction, which these rays also do.
A straight line (180o) is still an angle. Would you be wondering if the question said "Can 179o be a real angle?" No you would simply draw it. 1 degree more and you have 180o and it is an angle as well.
So you have a line that is both a line and an angle with A in the middle.
