Answer:
We see an object when light falls on it and gets reflected from its surface and enters our eyes. In a dark room, there is no source of light. no light falls on the surface of objects and we do not see them. This is why we cannot see the objects in a dark room.
your account has enabled profile pictures for your users, you can manage all profile pictures for your account. Profile pictures are public and automatically approved when users upload an image in their settings. Using profile pictures can make it easier to see the users in your account and managing them gives you the ability to keep the pictures appropriate.
If Gravatars are enabled for an institution in account settings, and a user has a Gravatar but chooses not to upload a profile picture, the Gravatar will display for the user's profile picture.
If a student views another student's user details in a course and reports a profile picture as inappropriate, you can review those profile pictures and approve, lock, or delete the picture. In the courses, instructors can remove profile pictures completely from a user's details page.
Many sockets have existed throughout history but only three are relevant today. These are LGA, PGA and BGA.
B is better than any other one's I think.
