Star formation begins when a.
gas and dust collapse inward.
c.
the fusion of hydrogen slows down.
b.
nuclear fusion starts in the core.
d.
the core becomes carbon and oxygen.

Please select the best answer from the choices provided
(Space and Environment)

option c is the correct answer.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.

e2020 answer: spores

pteridophytes

bryophytes

nonvascular

vascular