In the graph above, how does the acceleration at a compare with the acceleration at b?
a.
the acceleration at a is positive and less than the acceleration at b.
b.
the acceleration at b is positive and less than the acceleration at a.
c.
the accelerations at a and b are each zero.
d.
the accelerations at a and b cannot be determined.

This is a speed/time graph.
The slope of the graph at each point is the time rate of change of speed
at that point, and THAT's the definition of the magnitude of acceleration.

The slope of the curve is zero at both ' A ' and ' B ', so acceleration is
zero at both of those points.

That seems to be exactly what choice-c says.

Answer body lying face up ;

You need to be more specific.  i really don't know what a "motion map" is.you can draw a graph of an object's position, distance, displacement, speed,velocity, or acceleration versus time, or you can draw a graph of the object's x-position versus its y-position and not give any information about time at all.if the graph presents position or displacement against time,  then constant velocity is a straight line . . i.e. a line that has  constant slope.if the graph shows speed against time, then constant velocityis a horizontal piece of line.if the graph shows acceleration against time, then constant  velocity is a piece of line that lies on the x-axis . . it's value is zero.