Match the chemical conversions in Column I with the appropriate reagents in Column II and select the correct answer using the code given below the lists.
A. P = 2, Q = 3, R = 1, S = 4
B. P = 3, Q = 2, R = 1, S = 4
C. P = 2, Q = 3, R = 4, S = 1
D. P = 3, Q = 2, R = 4, S = 1