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]:
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.
This is puzzling.
I have just checked the back end DB and the answers that you thought were correct match the database.
I have ticketed this to be checked.
Thank you for taking the time to let us know.