Author a raw QTI 2.1 assessmentItem XML file for a multiple-choice question with response declaration and processing

Steps

1. Declare the candidate's response variable in a <responseDeclaration> child of <assessmentItem>, setting identifier (e.g. RESPONSE), cardinality="single", and baseType="identifier".
2. Inside the responseDeclaration, add a <correctResponse> element containing a <value> equal to the identifier of the correct <simpleChoice> (e.g. ChoiceA).
3. In <itemBody>, add a <choiceInteraction responseIdentifier="RESPONSE" maxChoices="1"> whose responseIdentifier matches the responseDeclaration identifier exactly, containing one <simpleChoice identifier="..."> per answer option.
4. Add a single <responseProcessing> element (QTI 2 permits only one per item) that references a predefined template by URI, e.g. http://www.imsglobal.org/question/qti_v2p0/rptemplates/match_correct, or contains custom <responseCondition> logic.
5. For partial-credit scoring instead of match_correct, use the map_response template together with a <mapping> containing <mapEntry mapKey="..." mappedValue="..."/> entries inside the responseDeclaration.
6. Declare an <outcomeDeclaration identifier="SCORE" cardinality="single" baseType="float"/> so response processing has a variable to write the computed score into.