A biologist wants to study the effect of vitamin D enriched food on theweight of adult mice. Would an experimental or observational study design be more appropriate?

Select the correct answer below:

An observational study should be used because the type of food consumed cannot be controlled.

An observational study should be used because theweight of adult mice cannot be controlled.

An experimental study should be used where the food consumed is the controlled factor.

An experimental study should be used where theweight of adult mice is the controlled factor