When configuring a data page that needs to retrieve details of a single record, the appropriate source to use is:
D: Lookup. Lookup is specifically used in Pega to retrieve a single record based on a key or a set of keys from a data type. This makes it suitable for data pages that are intended to provide detailed information about a particular entity, ensuring efficient and accurate data retrieval based on specific criteria.

To implement a requirement where different processes are applied based on customer card types:
C: Add a custom condition to start the process by testing the card type. This solution involves setting a condition at the beginning of the Employment Information process that checks the type of credit card (standard or platinum). If the condition identifies a platinum card, the process is skipped, aligning the process flow with the specific requirements of different cardholders.