If you wanted to add an expiration date to the URL’s which are provided by Cloudfront, how would you go about doing that.

Answer options:

A.Set an expiration date for the Cloudfront distribution. This would then add the same date to the URL’s
B.Use a signed URL’
C.Use cookies to embed the expiration date.
D.This is not possible with Cloudfront

Answer - B
A signed URL includes additional information, for example, an expiration date and time, that gives you more control over access to your content. 
For more information on signed URL’s, please refer to the below URL:
http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-signed-urls.html