The nurse in Armando’s doctor’s office leaves him a voicemail about his bloodwork. She mentions that everything looked good except one reading. She tells Armando not to worry—just make sure he gets out in the sunlight on a regular basis and he should be fine. Considering this advice, which micronutrient is Armando MOST likely low on?

A.
magnesium

B.
iron

C.
calcium

D.
vitamin D