Agovernment policy that sharply raises taxes, a dramatic decline in the birth rate, and a lengthy war all contribute to a. decreased population b. increased population c. decreased pestilence d. increased pestilence

 A. decreased population

Details:

An article by Brittany De Lea for Fox Business (Jan. 2, 2019) notes that the "states where populations have grown the fastest over the past year include a handful with either low, or no, state income taxes."  Her report goes on to say: "On the other hand, in some higher-tax states, populations actually shrank. In New York, for example, where state income taxes extend up to 8.82 percent, 48,510 people left the state."  Over 45,100 people also left Illinois, where the state income taxes recently increased by 25%.

A BBC article by James Gallagher (November 9, 2018) explains the connection between declining rates of women having children and decreased population.  "The total fertility rate is the average number of children a woman gives birth to in their lifetime.  ... Whenever a country's rate drops below approximately 2.1 then populations will eventually start to shrink."  The study on which Gallagher was reporting found that half of the countries in the world have fallen below that 2.1 fertility rate and may, as a result, eventually see population decline.

A lengthy war will have obvious detrimental effects on a nation's population.  In World War II, for instance, a total of over 70 million people were killed, which was  3% of the 1940 world population.  The USSR alone lost over 26 million people (soldiers and civilians) during that war, which was nearly 14% of its 1940 population.

d. japan's attack on pearl harbor