Match the metal in List I with the key extraction step in List II. List I: P. Fe Q. Cu R. Zn S. Al List II: 1. electrolysis of alumina dissolved in molten cryolite; 2. self-reduction of the sulphide with its own oxide in a converter; 3. smelting of the oxide with coke near $1673\mathrm{K}$ with the metal collected as vapour; 4. reduction of the oxide by CO in a blast furnace.

1. AP-4, Q-2, R-3, S-1
2. BP-4, Q-3, R-2, S-1
3. CP-2, Q-4, R-3, S-1
4. DP-4, Q-2, R-1, S-3