You have an app that captures live video of exam candidates. You need to use the Face service to validate that the subjects of the videos are real people. What ...

You have an app that captures live video of exam candidates.
You need to use the Face service to validate that the subjects of the videos are real people.
What should you do?

A. Call the face detection API and retrieve the face rectangle by using the FaceRectangle attribute. B. Call the face detection API repeatedly and check for changes to the FaceAttributes.HeadPose attribute. C. Call the face detection API and use the FaceLandmarks attribute to calculate the distance between pupils. D. Call the face detection API repeatedly and check for changes to the FaceAttributes.Accessories attribute.