At the time of the origin of luca which mode of nutrition was not being used?
a. chemoheterotroph
b. chemoautrophs.
c. photoautotrophs-oxygenic.
d. photoautotrophs-anoxygenic.

C. Photoautotrophs-oxygenic.

Explanation:

LUCA is an abbreviation of the ‘Last Universal Common Ancestor’. The LUCA was a microorganism which lived around 4 billion years ago. The evidence had shown that the LUCA was lived deep underground in hydrothermal vents. These vents were rich in iron-sulphur. It did not use air but made its food from the metal-rich environment surrounding it. It made organic compounds such as ammonia for its metabolism from elements such as hydrogen, carbon dioxide and nitrogen.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

thinking it would be d not too sure but i think it's right