This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
A study revealed that in a study group, intake of betacarotene decreases carcinoma of colon but it actually may be due to increased intake of dietary fibre. This is due to 
Select and explain. 
A. Confoundging factor, B. Misclassification bias, C. Randomisation, D. Sampling error
C: Randomisation
Answer: C: Randomisation 
Explanation: None