To make a VR app start in non-VR mode, which setting should be modified?

Modifying the VR SDK list by adding "None" at the top is the appropriate action to make a VR app start in non-VR mode. In Unity, the order of the VR SDKs in the list determines the priority for which SDK is activated when the application starts. By placing "None" at the top, it effectively tells the application to default to non-VR mode upon launch.

This approach allows developers to ensure that the application can run without requiring any VR hardware, making it accessible for users who may not have a VR headset or do not wish to enter VR mode right away. It also gives the developer greater control over how the application behaves during startup, catering to various user experiences and expectations.

Other configurations, such as setting the default mode to VR or selecting a specific VR device, would lead to the application prioritizing VR functionality instead of starting in a standard mode. Adding a VR headset requirement would inherently make the application dependent on VR capabilities, which is contrary to the goal of starting in non-VR mode.