Fermentation

In C plants, the initial fixation of carbon dioxide occurs in the mesophyll cells. The primary CO acceptor is Phosphoenol Pyruvate (PEP).
The enzyme PEP carboxylase catalyzes the reaction between CO and PEP to form oxaloacetic acid (OAA). This adaptation allows C plants to efficiently fix carbon even under conditions of high light intensity and temperature, minimizing photorespiration.
By contrast, in C plants, the primary acceptor of CO is Ribulose-1,5-bisphosphate (RuBP), and the enzyme involved is Rubisco.
Hence, in C plants, the correct primary CO acceptor is Phospho enol pyruvic acid (PEP).

Fermentation is an anaerobic process occurring in the absence of oxygen. It results in partial breakdown of glucose and yields only 2 ATP per molecule. Oxygen is not required, and NADH is used in the process rather than produced in net gain.