Answer:
(a) Because cancer cells grow in an anaerobic environment
Step-by-step explanation:
Cancer cells grow in an anaerobic environment so they cannot use the usual oxidative phosphorylation. They use the last compound generated through glycolysis (pyruvate), convert it to lactate, and start the lactate pathway. Even in conditions with high oxygen concentration, cancer cells do this, and it is thought that it is because they have some damage in mitochondrial activity but it is not proved, this is called the Warburg effect.