A model risk team is reviewing a customer lifetime value prediction model. They find the model was developed using only customers who remained with the company for at least two years, excluding churned customers. What model risk does this introduce?

Here's the deal — d is correct because excluding churned customers introduces survivorship bias in two compounding ways: the model has never learned the patterns of customers who left (causing it to underpredict churn risk and lifetime value for those profiles), and it overfits to the characteristics that distinguish loyal customers (reducing generalizability). Both A and C accurately describe consequences of survivorship bias in this context.