By this time P : at the railway station Q : reported mass looting R : reports of violence were flooding in S : which police dispatches The Proper sequence should be:

The correct answer is: A. RSPQ

The sentence is about reports of violence flooding in, which police dispatches reported. The reports of violence were flooding in at the railway station. So the correct sequence is:

R – reports of violence were flooding in
S – which police dispatches reported
P – at the railway station
Q – reported mass looting

The other options are incorrect because they do not follow the correct sequence of events. For example, in option B, the reports of violence are reported before they are flooding in. This is not possible, as the reports cannot be reported until they have flooded in.