The following six sentences come from a paragraph. The first and the last sentences are given. Choose the order in which the four sentences (PQRS) should appear to complete the paragraph:
S1: An experiment was conducted in England to study what happens to the bodies and minds of people travelling at high speeds.
S6: Psychological tests showed that their ability to make decisions decreased quickly.
P: Then they were flown to America.
Q: Travelling also had an effect on the minds of these people.
R: They were first kept under observation in London.
S: It was found that as they travelled from one time zone to another, their blood pressure moved away from the normal.