Set \(P\) consists of the first \(n\) positive multiples of \(3\) and set \(Q\) consists of the first \(m\) positive multiples of \(5.\) The sum of all the numbers in set \(P\) is equal to \(R\) and the sum of all the numbers in set \(Q\) is equal to \(S.\) If \(m\) and \(n\) are positive integers, is the difference between \(R\) and \(S\) odd?
(1) \(m\) is odd and \(n\) is even.
(2) \(m\) can be expressed in the form of \(4x +3\) and \(n\) can be expressed in the form of \(2x,\) where \(x\) is a positive integer.
Answer: E
Source: e-GMAT