In each question, the first and the last sentences of the passage are numbered S1 and S6 respectively. The rest of the passage is split into four parts. These four sentences are jumbled. Read the sentences and identify their correct and logical order.

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S1: Most of the perishable foods are shipped by refrigerator ships.
P: They are placed in the refrigerated hold of the ship.
Q: Some foods, such as bananas, are shipped before they get ripe.
R: As the green bananas are loaded, a man watches closely the signs of yellow on them.
S: The cool temperature keep the bananas from getting ripe during the trip.
S6: Ripe bananas are poor travellers and even one ripe banana at the start of the trip can spoil a whole ship load of fruit.
The Proper sequence should be: