Explanation
Two methods that will allow the architect to meet the requirements for creating a custom team solution on the custom Loan object are creating a custom trigger on the Custom Team object that inserts or updates records in the Loan_share object, and creating Apex Sharing Reasons on the Loan object to identify the reason the Loan record was shared. The custom trigger can use Apex Managed Sharing to grant Read Only or Read/Edit access to the Custom Team members based on the Primary field value. The Apex Sharing Reasons can be used to distinguish between different types of sharing and provide more granular control over access