Which option lists only pre-columbian indian groups that lived in the southwest?

it might look like that the ideal way to research the health effects of trans fats is through a controlled experimental feeding trial. but these kinds of trial have several important limitations that the researcher must look into:

short in duration (this factor usually checks up on the intermediary risk factors rather than the actual outcomes of the disease)

limited dietary changes

only makes use of healthy participants

for the full pic, im also im american school, and my picture was glitched