Question

It’s either D or E; please help

Answer 1

Answer:

They should be blocked by body fat composition so the subjects are as similar as possible.

Step-by-step explanation:

It's D .

Blocking here means how should the subjects be arranged in terms of body fat or weight.

Option A is wrong because alphabetically controlling body fat would not get desired results.

Option B is wrong because different age groups would yield different results.

Option C is wrong also because weight loss is not dependent on taller people.

Option D is correct because controlling body fat would yield best possible results in ascending or descending order

Option E is incorrect because  arranging data in ascending or descending order would simplify the researches experiments.