Today I started having a discussion about how acceleration should be considered constant if its numerical value is zero because '0' is also a numerical constant. There was a contradiction stating that acceleration=0 should not be considered constant because the rate of change in velocity doesn't exist in that case (basically there is no acceleration) hence 0 will not be considered constant in this case. I think as the numerical value of acceleration is not changing it should be constant.
I am providing the question that started this whole discussion and what I believe to be the answer.
The displacement-time graph of a moving object is a straight line. Then,
(a) its acceleration may be uniform
(b) its velocity may be uniform
(c) its acceleration may be variable
(d) both its velocity and acceleration may be uniform
In the attached question I think the last option will be correct because yes, a graph showing constant acceleration can also have zero acceleration. It should be totally possible as 0 is a constant.