The gaseous oxygen in the Earth's atmosphere was produced as a ...

[mspears3]

The gaseous oxygen in the Earth's atmosphere was produced as a by-product of
 
  A) volcanic outgassing.
  B) photochemical reactions breaking down ozone (O3 ) to form oxygen (O2 ).
  C) photosynthesis.
  D) decay of organic matter.

Question 2

The deepest places in the ocean are those in which rifting occurs.
 
  Indicate whether the statement is true or false

[ktidd]

Answer to Question 1

C

Answer to Question 2

FALSE