STYGIAN: extremely and unpleasantly dark
DARK: with little or no light
1.Abysmal:very bad
Low:not measuring much from the base to the top
2.Cogent: a cogent argument, reason, etc. is clearly expressed and persuades people to believe it
Contentious:casung or likely to cause disagreement
3.Fortuitous:not planned,happening by chance
Accidental:something bad that happens that is not expected or intended and that often damages something or injures someone
4.Reckless:doing something dangerous and not worrying about the risks and the possible results
Threatening:expressing a threat of something unpleasant or violent
5.Cataclysmic:an event that causes a lot of destruction or a sudden, violent change
Doomed:certain the fail,die, or be destroyed
The answer would be 3.Fortuitous , Accidental.