Aparticular system of thought or doctrine is called
a philosophy
an oligarchy
a diaspora
a messiah

A particular system of thought or doctrine is called a philosophy. Oligarchy is related to business or country held by a small group of people. Diaspora pertains to people leaving outside their hometowns or countries. Messiah is an omnipotent Christian god.

studies show tha in 7.5 billion years from now, the expanding sun will engulf, and destroy, the earth.

b: to eliminate competition from other farmers