Wrong answer or wrong description for “The AWS STS API supports which of the following methods of access? (Choose 3)”

The choices are:

A Azure AD Federation

B Kubernetes Federation

C Web Identity Federation

D Cross Account Access

E Active Directory Federation

I selected C-D-E

The "wrong answer" explanation shows A as a correct answer and C as a wrong answer. The response is [annotations mine]:

Sorry!

STS enables Web ID Federation [C], AD Federation [E] and Cross Account Access [D]. 

On reviewing the STS documentation, there is no reference to Azure AD federation superficially visible, but C, D, and E are all referenced.