Seems like a fantastic filter question to me. It's basic, it's not an unfair or trick question, there are multiple valid options that the candidate can respond

Seems like a fantastic filter question to me. It's basic, it's not an unfair or trick question, there are multiple valid options that the candidate can respond with - you're not fishing for your single pet solution - and a strong candidate could demonstrate ability by going into more depth and mentioning multiple options and explaining when one option would be preferred vs others. Keep asking it. If you're seeing a high rate of candidates who can't answer it at all, that suggests that the population of candidates who are applying for your roles are really poor fits for the role. Maybe worth exploring if there's ways you could change how the roles are advertised to access a different population of candidates, or perhaps ask this basic question earlier in your hiring pipeline -- e.g. as an automated screening question as a pre-req to interviewing with humans.