Which statements are correct for service contracts?

Which statements are correct for service contracts?

A.
Each SOA Serviceincludes a service contract.

B.
When using web services, the WSDL for the web service is the service contract.

C.
A service contract defines the functional and non-functional capabilities provided by an SOA
Service.

D.
A service contract defines which clients are allowed to access a particular SOA Service.

E.
A service contract is optional documentation that might be provided for an SOA Service.

Explanation:
A: All Services must have a contract that adheres to a predefined template.
C: A contract describes the Service in human-readable terms, enabling a solution
designer to determine its capabilities and characteristics. It includes both functional
and non-functional terms. The functional aspect of a contract describes the available
operations of a Service and their functional capabilities. It should be stated using
business terms, in order to promote alignment of Services to business concepts.
Contracts also specify non-functional aspects of Service, such as invocation protocols,
security requirements, semantics, transaction requirements, invocation style, quality of
Service, etc.
Reference: Oracle Reference Architecture,SOA Foundation, Release 3.1