How Do Some Cyanobacteria Fix Nitrogen While Growing Aerobically

Multiple Choice

How do some cyanobacteria fix nitrogen while growing aerobically?

A) They do not, because nitrogenase is destroyed by oxygen.
B) They use special cells called heterocysts that protect the enzyme.
C) They use spores that protect the enzyme.
D) They do it using no special structures or mechanisms.
E) They live symbiotically with other organisms that protect the enzyme.