Final answer:
The antonym for 'fortuitous' is 'hapless,' representing the opposite of experiencing good fortune or luck.
Step-by-step explanation:
The antonym for "fortuitous," which is an adjective or adverb meaning happening by accident or chance and synonymous with lucky or fortunate, is b) Hapless. This choice best represents the opposite of being fortunate or experiencing good fortune. In the context of discussing unusual or extraordinary events, those that are fortuitous tend to be seen as positive and beneficial, like winning the lottery. In contrast, to be hapless is to be unfortunate, often finding oneself in unlucky circumstances without hope of improvement.