Answer is C.

B.
The correct approach to implement this request would be to create a controller extension. By using a controller extension, the developer can access both the Account and Contact objects and retrieve the necessary fields to display on the Visualforce page. Additionally, the developer can use the standard controller to retrieve the related Contacts for the Account and display the fields configured on the page layout for the Contact object.

Using the apex:include tag is used to include a Visualforce page within another page, but it does not help in accessing the Contact object's fields configured on the page layout.

Using the apex:relatedList tag is used to display a related list of records for a specific object, but it does not allow for displaying fields configured on the page layout.

Adding a method to the standard controller would not help because it only provides access to the Account object's fields and not the related Contact object's fields.