Brother/Sister your correct answer will be:-

Scientist don’t know yet what creates life. But, since life evolves on earth, after it appeared here, it was only a matter of time before it spread to the whole world. Why? Because for our life, the earth is about an endless source of food and resources. Even if conditions change (atmosphere composition, sea composition, temperature), life will evolve and find a way to adapt (as it has done countless times already). This is a trait life on earth has.

We should look for these things in a planet in order to log it as candidate to contain life:

• High concentration of electronegative/electropositive elements available in the atmosphere/environment (to allow basic chemical reactions that life may need: on earth, life adapted for oxygen);

• Low and stable income of radiation (because radiation disrupts complex molecules much faster than life could or would bear);

• Enough distance from the sun so as to not be highly influenced by solar flares (also because of radiation). Though red dwarves last for much longer than K-type stars such as our sun, it’s debatable if earth-like lifeforms would be able to live in a red dwarf system, because the habitable zone around that kind of star is simply too close and the planet would suffer a lot in the early ages with solar flares, let alone keep an atmosphere;

• Some kind of protection against “fast-events” (fast-events being defined as those that change conditions faster than life can adapt to them: meteor strikes, planetary collisions, gamma ray bursts, solar flares, etc.);

If I had to bet, I would say none of these conditions are mandatory for life to appear and thrive, at least not if you consider the possibility of other types of life (gamma ray autotrophes, silicon-based lifeforms, etc.). However, it seems they are needed, or a given planet will just be steryle. Anyway we still know very little about life on other planets since we have right now just the earth and mars as planets in the habitable zone for us to study, which signifies a very low sampling to even make the most basic conclusions without a high chance of error.

✌︎Thanking you, your one of the Brother of your 139 Crore Indian Brothers and Sisters.✌︎