Which statement is incorrect for Rubisco?
Short answer
D

Background
A. Is correct, as it is the most abundant enzyme on land, and probably also in marine environments (Raven, 2013).

B. Is correct, as Rubisco catalyzes the carboxylation, or oxygenation reaction depending upon the molecular concentration of CO2 or O2 (Sudhakar et al., 2016).

C. Is correct, as it reveals the inefficiency of Rubisco, as CO2 and O2 compete for the active site. Fixation of O2 during photosynthesis oxidizes ribulose‐1,5‐bisphosphate into 3‐phosphoglycerate and phosphoglycolate - which is basically a waste of energy.  

D. Is incorrect and hence the answer to your question: Rubsico is present in CAM plants.

E. Because of the photorespiration described under B &amp; C, Rubisco is indeed regarded to be inefficient.

References
- Raven, New Phytologist (2013); 198(1): 1–3
- Sudhakar et al., Phenotyping Crop Plants for Physiological and Biochemical Traits, 2016