Which of the following is not a factor affecting population.
a. fertility
c. population pyramid
b. life expectancy
d. net immigration

Actually, all of them affect the population size (that's what I understand under "population". But "population pyramid" doesn't affect it directly - so it's the correct choice. Population pyramid is just a description of the age of a population, but it can tell us for example that a population is aging - signaling a decrease in size. 

The answer is d if you are on edgenuity. 

Answerbecause of improved transportation, communication, and other advantages;