Alex travels the 200 meters distance between points A and B in 40 seconds and the 500 meters distance between points B and C in 50 seconds.

Option A)Alex’s average speed (in m/s) while traveling from point A to C
Option B)7.6

The answer should be D,
Like if A—B----C, In this condition total distance = 700 and time is 90 , avg speed = 7.7777…(So option A)
But If C----A-----B, In this condition total distance = 300 and time is 90, avg speed = 3.33…(So option B)

Finally we end up choosing D.
This is a QC question(Under the tag distance/rates/Work)

Even if it is C-----A------B, Alex has to travel 500 meters from B to C right? So I think in any case it should be 700/90 = 7.8
What is the official answer?

Ahh I think I bought in physics, So what I meant was if he traveled From A to B towards west and then from B to C Towards East, then the difference between the distance of points A and C would be 300(but actually its displacement) My bad. Thanks Naikshriyans yes anycase total distance remains same