You provisioned the Face service in Azure. While you analyzed the results of a set of face data, you observed inefficiencies in analysis where the face was angled. In your coding you plan to use the necessary attribute to rotate the face for better analysis. Review the code snippet below and complete it by selecting the attribute to rotate the face rectangle. (select one answer choice) 
<pre class="brush:java;">if (face.FaceAttributes?................................ != null)
{
faceAngle = face.FaceAttributes.?.................................Roll;
var angleToPi = Math.Abs((faceAngle / 180) * Math.PI);
var newLeft = face.FaceRectangle.Left +
face.FaceRectangle.Width / 2 -
(face.FaceRectangle.Width * Math.Sin(angleToPi) + face.FaceRectangle.Height * Math.Cos(angleToPi)) / 2;
var newTop = face.FaceRectangle.Top +
face.FaceRectangle.Height / 2 -
(face.FaceRectangle.Height * Math.Sin(angleToPi) + face.FaceRectangle.Width * Math.Cos(angleToPi)) / 2;
left = (int)(newLeft * scale + uiXOffset);
top = (int)(newTop * scale + uiYOffset);
}
</pre> 

Answer options:

A.FaceRectangle
B.Occlusion
C.Exposure
D.HeadPose

Correct Answer: D 
Here is the completed code: 
<pre class="brush:java;">if (face.FaceAttributes?.HeadPose != null)
{
faceAngle = face.FaceAttributes.HeadPose.Roll;
var angleToPi = Math.Abs((faceAngle / 180) * Math.PI);
var newLeft = face.FaceRectangle.Left +
face.FaceRectangle.Width / 2 -
(face.FaceRectangle.Width * Math.Sin(angleToPi) + face.FaceRectangle.Height * Math.Cos(angleToPi)) / 2;
var newTop = face.FaceRectangle.Top +
face.FaceRectangle.Height / 2 -
(face.FaceRectangle.Height * Math.Sin(angleToPi) + face.FaceRectangle.Width * Math.Cos(angleToPi)) / 2;
left = (int)(newLeft * scale + uiXOffset);
top = (int)(newTop * scale + uiYOffset);
}
</pre>Option A is incorrect because FaceRectangle is not the correct face attribute.
Option B is incorrect because the Occlusion attribute is used to identify if there are any objects blocking the face such as eyes or mouth.
Option C is incorrect because the Exposure attribute is used for the exposure level of the image such as underExposure, goodExposure or overExposure.
Option D is correct because the HeadPose attribute is used for rotating the face rectangle. It is very helpful in scenarios where the face is angled.
Reference:
To learn more about using the HeadPose attribute, use the link given below: 

https://docs.microsoft.com/en-us/azure/cognitive-services/face/face-api-how-to-topics/how-to-use-headpose