Option C: Standard controller and the recordSetVar page attribute
Correct Answer.
Using the recordSetVar attribute with a standard controller enables the Visualforce page to access a set of records selected from a list view.
This allows users to edit multiple records.
recordSetVar is used with standard list controllers, not custom controllers.
Option A: Controller Extension and <apex:listButton> tag
Incorrect.
There is no <apex:listButton> tag in Visualforce.
Option B: Standard Controller with Custom List Controller extension
Incorrect.
A custom list controller extension is unnecessary when using recordSetVar with a standard controller.
Conclusion:
The Visualforce feature is Standard controller and the recordSetVar page attribute, which is Option C.
Reference:
Using Standard List Controllers
Option D: Custom List Controller with recordSetVar page attribute
Incorrect.