Answer:
Desire for more citizens
Step-by-step explanation:
Imperialism is defined as the domination of one country over other country through using military forces, political influence, or other means.
There are several causes of imperialism that include need for raw materials to control a supply of raw materials over countries and spreading Christianity is also a cause of imperialism as establishment of church and force people to convert new members into Christians.
Desire for more citizens is not a cause of imperialism do not focus on increasing population.
Hence, the correct answer is "Desire for more citizens".