Now the question was a good question on the basics, I am NOT disputing that !
[rant]
http://msdn.microsoft.com/en-us/library/ms175997.aspx
From the above reference (bolding added for emphasis)
COUNT(*) returns the number of rows in a specified table without getting rid of duplicates. It counts each row separately. This includes rows that contain null values.
COUNT(ALL expression) evaluates expression for each row in a group and returns the number of nonnull values.
From past experience, many have learned the adage, do not trust all that you read on the web And yet here the support for the correct answer(s) is a blog posting, while there is a reference readily available from MSDN
QODs using images instead of easily cut and paste text have now been excluded from being published, I would propose to the powers that be that those submitted QODs that can not use either a BOL, MSDN or Technet refrence to support the correct answer(s) also be excluded from publication.
[/rant]