A third person limited narrator and third person ominscient narrator differ in what way

Athe rate increases as income increases

True blindness may be caused by trauma to the eye, severe conjunctivitis due to  ibr (infectious bovine rhinoceros) or pink eye or other infections, leptospirosis, lead poisoning, selenium toxicity, fungal infections, vitamin a  deficiencies, rabies, vitamin b12 deficiency, neoplastic of the orbit or  conjunctiva, cataracts, congenital malformations, etc. 

Ais your best bet because all the others seem a bit incorrect 

Two million u.s. military remained segregated during the war