Which is NOT a challenge for spacecraft exploring the outer Solar System.

ong communication time

lack of sunlight for solar panels

long flight times

high temperatures

I do believe it's the lack for solar panels because there is always a type of sunlight to give energy to the spacecraft

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

the answer is c most of the fortnite players usually buy v bucks to get the battle pass and other cosmetics but some players who are referred to as "no skins" don't   buy skins and are usually noobs.

read more on -