Why are periods the most fundamental time unit? What will be ...

[anshika]

Why are periods the most fundamental time unit?
 
  What will be an ideal response?

Question 2

The Precambrian witnessed the development of
 
  A) the first atmosphere.
  B) the ozone layer.
  C) photosynthesis.
  D) photosynthesis, an oxygenated atmosphere, and the ozone layer.

[bfulkerson77]

Answer to Question 1

Answer: Periods are small enough time units to chronicle major changes in life forms. Eras are far too big, and epochs are too small.

Answer to Question 2

Answer: D

[anshika]

TYSM

[peter]

Thanks for the timely response, appreciate it