The best and most correct answer among the choices provided by the question is the fourth choice "Imperialism"
Imperialism, in a broad sense, is a political theory where a country (usually an empire or kingdom) extends its power by acquisition of territories. It may also include the exploitation of those territories which is similar to colonialism which is generally regarded as an expression ofimperialism.
I hope my answer has come to your help. God bless and have a nice day ahead!
