They changed over time by finding the right ingredients such as iron, metal, or steel to forge different creations. They took so slowly because no one was discovered the things to make stone tools.
The correct answer is It relates results to an original event.
One of the ways to improve arguments in a text is by using cause and effect structures.
Humans have 5 stages ofor sleep, stages 1,2,3,4,5 . They don't really have specific names , but for example stages 1 and 2 are typically characterized as "light sleep" Stages 3 and 4 are "Middle sleep" and part of 4 and 5 are REM. Part two of your question is REM (Rapid Eye Movement) which occurs in stages 4-5.
I recently did a speech on this Topic! Let me know of you don't understand ! I hope this helps! :)