Cross-Validation in Finance

Read the article entitled Cross-Validation in Finance and answer based on the article, the following 3 questions, each In around 3-5 sentences (per question) What is cross-validation? Describe how a k-fold cross validation works. What are the two reasons k-fold cross validation fails in finance? This part should be delivered in an APA Format Word document, where the article is the only reference. As it can be seen, it should be around 15 sentences to ensure that each answer is provided in depth. You can write more if needed, but that represents the minimum