A scientist constructs a graph to show the age structure of the human population of Country Y. The graph is shown here.

What conclusion is supported by the graph?
a. The population is decreasing because there are fewer older members than younger members.
b. The population is relatively stable because there are fewer older members than younger members.
c. The population is relatively stable because the death rate is about the same as the birthrate.
d. The population is increasing rapidly because of the youth of the population.