With reference to the formal proof of validity of the following argument, state the correct order of rules employed.  
1. \( P \cdot Q \)  
2. \( ( P \vee R ) \supset S / \therefore P \cdot S \)  
3. P  
4. \( P \vee R \)  
5. S  
6. \( P \cdot S \)  
A. Conjunction  
B. Modus Ponens  
C. Addition  
D. Simplification  
Choose the correct answer from the options given below: