13. Which is a characteristic of a stable climax community? (1) The number of pioneer organisms is increasing.
(2) Shrubs are replacing climax trees.
(3) Populations have reached equilibrium.
(4) Lichens are usually the dominant form of life.

the answer to you question is   jet streams

the supermassive black hole is in the middle of the galaxy.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

you can have just about every answer you can think of