Question

Statement: NASA has logged another extraterrestrial first on its latest mission to Mars: converting carbon dioxide from the Martian atmosphere into pure, breathable oxygen. The instrument that was used for the purpose works through electrolysis, which uses extreme heat to separate oxygen atoms from molecules of carbon dioxide, which accounts for about 95% of the atmosphere on Mars.
Assumptions:
I. There is no natural oxygen in Mars’ atmosphere.
II. Mars can now successfully support terrestrial life.

Q: Answer-Statement: NASA has logged another extraterrestrial first on its latest mission to Mars: converting...

The statement tells us that NASA can now produce breathable oxygen on Mars performing electrolysis on carbon dioxide, which makes up 95 of Mars atmosphere. It does not tell us what gases make up the remaining 5. Therefore, we cannot conclude that there is no natural oxygen on Mars. I does not follow. Oxygen alone cannot ensure that living beings will be able to survive and thrive on Mars. There are multiple other conditions that need to be fulfilled. II does not follow. Thus, d is the right answer.