What must happen before an igneous rock can form

Which statement best describes a keystone species? o a. it has littlelmenetic variation. it has an extremely high population. 0 b. 0 c. it remains unaffected by all environmental changes. od. it has a strong influence on the ecosystem. 0 e. it's the first species to populate a new ecosystem.

How does friction with the atmosphere affect the speed of an artificial satellite

Which of the following statements about protists are true? a.they are typically found in moist environments. b.they are all unicellular. c.they have a nucleus. d.they are all multicellular.