Answer:
Due to peace situation, urbanization and end of isolationism.
Explanation:
The role of samurai greatly changed from 1100 CE to 1850 CE. in the beginning, samurai used by the kings for defending their territories against enemies but later the peaceful rule of two and half centuries of Tokugawa and his descendants decreases the necessity of samurai so they are decrease in number with the passage of time. The main reason of decrease in number of samurai is urbanization and end of isolationism.
D I think since there are children in a factory :)
