The Amazon EC2 web service can be accessed using the _____ web services messaging

protocol. This interface is described by a Web Services Description Language (WSDL)
document.

A.
SOAP

B.
DCOM

C.
CORBA

D.
XML-RPC

Explanation:
http://docs.aws.amazon.com/AWSECommerceService/latest/DG/WSDLLocation.html