Let's look at your answer choices...
A- You don't want to limit yourself to just one food group. Eating fruits and dairy are also beneficial.
B- This is a good way, but it doesn't cover other things like making sure you get enough of each food group.
C- This is true, because you'll get the nutrition from each food group like dairy, grains, fruits, meats
D- Again, this is good, and helpful, but it's not the best answer. Olive oil is also fatty.
So, in my opinion, it would be
"C. Eating a wide variety of foods."
Hope this helps!
