In the CAM plants, which of the following events will not occur during day time?

The metabolic pathway of CAM involves acidification, which occurs at night (during the dark) and deacidification, which occurs during the day time (in light). During night, the organic acid content of CAM plants increases and the pH of their cell sap decreases.

In dark (during night), when the stomata are open, the carbon dioxide combines with phosphoenol pyruvic acid (PEP) to form oxaloacetic acid (OAA) in presence of enzyme PEPcarboxylase.