(a) Consider the following data mining problems to be addressed by an online sales company:

1. Predicting the amount of money a customer would spend for the next month based on their purchase history.

2. Assuming that the company has created customer categories based on existing customers shopping habits, predicting the customer category for a new customer.

3. Creating targeted offers to customers for items frequently purchased together.

4. Flagging customers that exhibit unusual buying patterns.

Which data mining task should the company use for each of the above cases? Justify your response for each case.