A merchant requires the ability to configure contact information for their brick and mortar stores as a CSV file upload. The module already exists and contains an etc/adminhtml/system.xml file where the new field can be added.

61. A merchant requires the ability to configure contact information for their brick and mortar stores
as a CSV file upload. The module already exists and contains an etc/adminhtml/system.xml file where the new field can be added. 
How do you specify the class that will process the uploaded file?

A. <upload_model>\Magento\Config\Model\Config\Upload\File</upload_model>
B. <frontend_model>\Magento\Config\Model\Config\Frontend\File</frontend_model>
C. <backend_model>\Magento\Config\Model\Config\Backend\File</backend_model>
D. <source_model>\Magento\Config\Model\Config\Source\File</source_model>

Correct Answer: C