What does PA represent in the following reaction?

• A. \(\frac{[B_w]}{[A_w]}\)
• B. \(\frac{[B_{org}]}{[A_{org}]}\)
• C. \(\frac{[A_{org}]}{[A_w]}\)
• D. \(\frac{[B_{org}]}{[B_w]}\)