Factors such as literacy rate, average family income, infant mortality rate, and life expectancy are used most often to measure
a.
development
b.
happiness
c.
quality of life
d.
gross domestic product

Factors such as infant mortality rate, literacy rate, average family income, and life expectancy” are used to measure Development.

Explanation:

The term Development is related to the social and economic progress. The necessary conditions for development are growth. There are many factors used to measure Development such as Population growth, Urbanization, Infrastructure, Social conditions, etc.  

In these measures, social condition category includes the following: Literacy rate, Life Expectancy, infant mortality rate, health care, caloric intake, average family income, etc. Thus, the factors explained above are most often used for measuring Development.

a and b because with the other three, they simplify to something else.