Given below are two statements. Based on them,select the correct option given below.
Statement $I$: $N_2$ fixing heterocystic cyanobacteria is Anabaena.
Statement $II$: $N_2$ fixing Anabaena is symbiotic with lichens.

• A
  Statement $I$ is correct but Statement $II$ is incorrect.
• B
  Both Statement $I$ and Statement $II$ are correct.
• C
  Both Statement $I$ and Statement $II$ are incorrect.
• D
  Statement $I$ is incorrect but Statement $II$ is correct.