Which of the following is ideal to ensure similarity between experimental & control groups

Stratified randomization: Study population is ‘first stratified’ by each variable which is considered important, and then randomization is done to each treatment groups within each stratum. - Comparison groups become similar as possible as regards participant characteristics that might influence the response to the intervention - Equal numbers of participants with a characteristic thought to affect prognosis or response to the intervention will be allocated to each comparison group. - Stratification increase the likelihood that two groups will be more comparable.