Motion in a Straight Line

From the graph for first line, the slope is negative and intercept is positive.
So, equation of line is
v‌‌=−mt+c
a1‌‌=‌

dv

dt

=−m
Similarly, for second line, the slope is positive and intercept is negative, so equation of line is
v‌‌=mt−c
a2‌‌=‌

dv

dt

=m
∴ The corresponding acceleration-time graph as shown below Hence, option (a) is correct.