Explanation
The correct answer is to enable the OSPF toggle and to add an Area Definition for the Tier-0 gateway in the image. These two items are required to configure OSPF on the Tier-0 gateway, as explained in the web search results123.
To mark your answers by clicking twice on the image, you can double-click on the toggle switch next to OSPF to turn it on. The switch should change from gray to blue, indicating that the option is enabled. Then, you can double-click on the Set button next to Area Definition to add an area definition. A pop-up window should appear where you can specify the area ID and type.
1. Click the OSPF toggle to enable OSPF 2. In the Area Definition field, click Set to add an area definition
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2/administration/GUID-5BEC626C-5312-467D-B8