Explanation/Reference:
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.
Incorrect answers:
B: Ideally message exchange patterns will be described by the Service contract using human readable text while the formality of WSDL and WS-Addressing,etc. will be developed during the realization of the Service interface.
D: Just wrong.
E: It is required, not optional.
Reference: Oracle Reference Architecture, SOA Foundation, Release 3.1