A scientific researcher wants to investigate the effectiveness of a cholesterol-lowering medication. The 500 participants are first divided into three groups those whose IMI is under 40, those with a BMI botesen 40 and 45, and those with a BMI above 40. Within each group the participants are randomly assigned to one of four treatment groups. The first group will receive a low dose of the medication, the second group will receive a ligef dose of the medication, the third group will receive a placebo, and the fourth group will meet with a dietitian who counsels them on different diets to lower cholsterol. At the end of a 8- month period, each person's cholesterol will be fooled and the change in their cholesterol level will be recorded. Identify the type of study design used in this example A. Randomized block design, blocking on cholesterol level, with heo factors, Irealment and A level B. Randomized block design, blocking on treatment, with one factor, BMI level C. Completely randomized over two factors, freatment and BMI level D. Randomized block design, blocking on BMI level, with one factor, treatment E. None of the above