Which of the following points lies on the circle whose is at the origin and whose radius is 10?

You haven't listed any points, so it's kinda tough to help you
pick out the correct one.

Go through the list of choices ... you know, that list after the
question that you didn't show us ... and test each point.

If (the 'x' value)² + (the 'y' value)² adds up to 100, then
the point is on the circle.

Using pythagoras theorem, a is the only correct answer. B and c are wrong