The is one measure of the wealth in each country.
a. gross domestic product (gdp) per capita
b. rate of infant mortality
c. average life expectancy
d. dow jones industrial stock index

 A. gross domestic product (GDP) per capita

The Gross Domestic Product (GDP) per capita is one measure of the wealth in each country.

Explanation:

The Gross Domestic Product (GDP) per capita of a country can be derived by dividing the country’s Gross Domestic Product (GDP) by the population of the country. Thus, it is used in measuring the standard of living of the country which in turn shows how wealthy a country is.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

answer; education;