dear sadra
your suggestion is good but it needs more collaboration. ;D
no.13 the ans is C
STYGIAN: 1.dark or gloomy 2.infernal; hellish.
happening or produced by chance; accidental: fortuitous
cogent : to the point; relevant; pertinent.
cataclysmicf, pertaining to, or resulting from a cataclysm.
doomed:fate, condemnation, predestine.