Question

at which points is the train stopped on the distance - time graph?
a and b
b and c
d and f
b and d

Explanation:

On a distance - time graph, when the train is stopped, the distance does not change with time. This is represented by a horizontal line segment. If we assume that in the graph (not shown here but based on the options), the horizontal line segments are at the intervals corresponding to points \(B\) and \(D\) (since for a stopped train, \(distance\) \(s\) is constant, so \(\frac{\Delta s}{\Delta t}=0\) which is a horizontal line on a \(s - t\) graph).

Answer:

B and D