Case 3-2 Judy Has Begun to Apply the Basic Information That You

Multiple Choice

Case 3-2
Judy has begun to apply the basic information that you have given her about schemas, and she would now like your help in mastering the details of how schemas work. 
Judy has included the following element definition in her schema:
     <xs:element name="ingredient">
            <xs:complexType>
                  <xs:sequence>
                        <xs:element name="name" type="xs:string" />
                        <xs:element name="amount" type="xs:string" />
                  </xs:sequence>
            </xs:complexType>
     </xs:element>
-In her definition of the recipe element, Judy would like to reference the existing definition of the ingredient element. Which of the following element declarations accomplishes this?

A) <xs:element id="ingredient" />
B) <xs:element idref="ingredient" />
C) <xs:element name="ingredient" ref= "existing" />
D) <xs:element ref="ingredient" />