If 8 molecules of Ribulose 1, 5-bisphosphate molecules are oxygenated by RUBISCO, how many PGA molecules are ultimately available to PCR cycle in photosynthetic carbon oxidation cycle?

Question

$\begin {array} {1 1} (1)\;12 & \quad (2)\;16 \\ (3)\;24 & \quad (4)\;8 \end {array}$