In each of the following items, there is a sentence of which some parts have been jumbled up. You are required to rearrange these parts which are labelled P, Q, R and S, to produce the correct sentence. Choose the correct sequence and mark in your answer sheet accordingly.

The practice of taking performance-boosting drugs among athletes

P: but checking it is not

Q: going to be easy is generally conceded to be

R: unfair of the detection technology for the user

S: is generally one jump ahead

The proper sequence should be: