The first pathway of photosynthesis was

The first pathway of photosynthesis was
  a. the cyclic pathway.
  b. the noncyclic pathway.
  c. similar to anaerobic respiration.
  d. similar to aerobic respiration.
  e. based on the fermentation pathway.
 
 

Question 2

Which of the following is(are) TRUE of
  photoautotrophs?
  a. They are responsible for the first concentration
  of free oxygen in the atmosphere.
  b. They are responsible for an early extinction of
  most anaerobic organisms.
  c. They are carbon-rich food baskets for
  heterotrophs.
  d. They are responsible for the presence of the
  ozone layer of the atmosphere
  e. All of these are true.