If oxygen is allowed to be present only glycolysis will happen.
The pulmonary veins transport oxygenated blood back to the heart from the lungs, while the pulmonary arteries move deoxygenated blood from the heart to the lungs.)
It should be 3! That is the only logical answer to the question...
Its gone be b cause the organism can produce them out
I think the most suitable answer is carbohydrates as it can be monosaccharide, disaccharide or polysaccharide.