Read the following statements:
(a) At the time of Mendel, the nature of ‘factors’ regulating the pattern of inheritance was not clear.
(b) Over the next hundred years, the nature of the genetic material was investigated and found to be DNA for the majority of organisms. 

• A

  Only a is correct 

• B

  Only b is correct

• C

  Both a and b are correct

• D

  Both a and b are incorrect