It does sound like he may be struggling with anxiety about potentially get the wrong answer. Perfectionism is anxiety, really.
It could also be a language processing issue. Here’s some insights into that so you can determine if maybe it’s something you should explore.
Free Webinar Replay: “What Do You Mean?” Language Processing Deficits in Children with ADHD
Penny
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism