Statement I : As mentioned, RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is indeed the most abundant enzyme in the world and it plays a crucial role in the process of photosynthesis. It catalyzes the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants into energy-rich molecules such as glucose. Statement II : In C4 plants, the RuBisCO enzyme is physically separated from the oxygen in the leaf air spaces by concentrating it in bundle sheath cells. This significantly reduces its oxygenase activity and thus the rate of photorespiration, effectively making photorespiration minimal to non-existent under normal conditions. However, under certain conditions, such as extreme drought or high temperatures, photorespiration can occur in C4 plants as well. But in a standard environment, it's largely inhibited, making this statement correct.