As People Progress into Old Age,their Disease-Fighting Immune Systems Become

Multiple Choice

As people progress into old age,their disease-fighting immune systems become

A) more effective in resisting most life-threatening ailments.
B) less effective in resisting common cold viruses than in resisting cancer.
C) more effective in resisting upper respiratory flu than in resisting pneumonia.
D) completely ineffective in resisting any diseases without specific medication.