In the following items, each passage consists of six sentences. The first sentence (S1) and the final sentence (S6) are given. The middle four sentences in each have been removed and jumbled up. These are labelled P, Q, R and S. You are required to find out the proper sequence of the four sentences and mark accordingly on the Answer Sheet. 

S1: Mental disability, whether mental retardation or any other developmental disability, is not the same as in mental illness. 
P: A person with mental disability can certainly he helped to improve, but mainly in childhood. 
Q: But mental disability has no cure. 
​R: Mental illness has an identifiable · cause and may be cured. 
S:  Not the best doctors nor all the medicines in the world can cure mental disability. 
S6: And the earlier the better.