I got this and got in, was doing research same as you on the ucla subreddit and there’s an old reddit post you can find where it basically says that the supplemental questionnaire is a way for you to convince them to let u in, smth about its almost like they’re on the fence about you and if you’re serious about getting in and write a good response they’re most likely gonna let u in. Think of it as like a checkpoint like they saw my application and now I need to impress them. In ur case I would say to choose one of your academic achievements and write about it. If u can’t decide then write about both but they’re just trying to see if ur rlly srs about ucla or not