What’s best practice for including correct answers in tree tests?

Let's say I'm creating a tree test to validate my IA for a grocery shopping website. When I'm creating the tree, I'm wondering if I should include the target in the tree, or stop the tree at the next highest category. For instance:

If I want the customer to locate cucumbers. My tree might look like:

Vegetables > Green vegetables > Cucumber

Should I include cucumber in the tree, or should it stop at green vegetables?

My concern with including cucumbers is the participant might just search through until word association kicks in, while stopping it at green vegetables might make them think more critically about it.

Would appreciate your thoughts!