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
Which of these is not true about randomization in a clinical trial? 
Select and explain. 
A. Reduces confounding, B. Decreases selection bias, C. Ensures comparability of two groups, D. Increases external validity of the trial
D: Increases external validity of the trial
Answer: D: Increases external validity of the trial 
Explanation: Ans: D. Increases external validity of the trial(Ref Park 24/e p87, 23/e p82, 22/e p79)External validity is the validity of generalized (causal) inferences in scientific research, usually based on experiments as experimental validity.In other words, it is the extent to which the results of a study can be generalized to other situations and to other people.This cannot be ensured by randomization.