Over the past century,a marked decline in the mortality rates of many infectious diseases has been observed.Which of the following is the most likely reason for the observed decline in mortality rates from common infectious diseases?

A) Development of penicillin
B) Development of insulin
C) Development of vaccines
D) Improvement in social conditions
E) Worse sanitation and unsafe water

Mortality Rates

The measure of the frequency of occurrence of death in a defined population during a specified interval.

Infectious Diseases

Illnesses caused by pathogens such as bacteria, viruses, fungi, or parasites that can be spread, directly or indirectly, from one person to another.

Penicillin

A group of antibiotics derived from Penicillium fungi, used in the treatment of bacterial infections.