Your question is Diagnosing and Mitigating Overfitting. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
How do you diagnose and mitigate overfitting in high-dimensional models?
Discuss a practical workflow for detecting overfitting, separating it from data leakage and distribution shift, and selecting mitigation techniques. Address validation design, regularization, feature selection, model complexity, and the metrics or plots you would use to verify that the solution generalizes.