The first organisms on primitive earth were

On the primitive earth there was no molecular oxygen and an anaerobic environment existed there. So, it is believed that the organisms at that time had used organic compounds for their energy source and are therefore heterotrophic.

Since organisms had used direct organic compounds as their energy source and had not synthesized their own food, they were not autotrophic. Also, there were no other life forms on which they can reside as a parasite, they were also not parasitic.

Since there was no oxygen at that time and organisms had used organic compounds as their energy source, first organisms on earth were heterotrophic and anaerobic.

Therefore, the correct option is (b) heterotrophic and anaerobic.