Arunner is training for a marathon. he follows a trail going 5m/s n, then 2.5m/s s, then 4 m/s n and finishes strong going 7m/s w. what is the resultant velocity in km/h of the cyclist throughout the training session

In order to calculate his velocity for the whole session, we need to know ...

(1).  the straight-line distance from the start-point to the end-point;

(2).  the direction from start-point to end-point

(3).  the elapsed time from start to finish

We could find (1) and (2) if we knew how much time he spent on each segment of the training run.  Then we could calculate the distance covered on each segment, and construct the straight-line displacement and direction of the whole thing.

For (3), no time information is given anywhere in the question, so it's pretty hard to come up with a total time.

We definitely have to mark this one "INSUFFICIENT GIVEN INFORMATION".  We just don't have what we need in order to solve it.

d is the correct answer