Which of the following statements best describes comets and asteroids? PLS HELP

A.

Both asteroids and comets have long tails.

B.

Comets are made from frozen ice, gas and dust; but asteroids are made from rock and/or metal.

C.

Comets orbit the sun, but asteroids orbit the moon.

D.

Both comets and asteroids are surrounded by a hydrogen cloud.

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Put the following steps of the convection process in the correct order. 1. gravity pulls cooler matter downward. 2. the matter expands and decreases in density. 3. an up-and-down flow of matter produces a convection current. 4. matter is heated. 5. warmed matter is forced upward. question 2 options: a) 4, 2, 5, 1, 3 b) 2, 4, 3, 1, 5 c) 3, 2, 5, 4, 1 d) 1, 4, 2, 5, 3

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?