Arrange the sentences P, Q, R and S in the correct order to form a meaningful paragraph.

P: Within minutes, a long line of buses, cars and scooters had piled up behind it.
Q: In the end, a vegetable seller led it gently to the roadside, holding out a bunch of spinach.
R: Yesterday morning, a cow sat down in the middle of the busiest road in our town.
S: Their drivers honked and shouted, but the cow did not move.