Which of the Following Best Describes the Effect of Aging

Which of the following best describes the effect of aging on the immune system? 

A)  Immunity is improved by abundant intake of iron-rich red meats and calcium-rich butter. 
B)  In the United States, infectious diseases rarely cause of deaths in the elderly. 
C)  Immune function does not decline with age in people who maintain good nutrition. 
D)  Antibiotics are often ineffective in treating infections in older people who have deficient immune systems. 
E)  In elderly persons, nutritional status rarely influences immune functioning.