The correct answer is B

Correct Answer is B.

#["The payload is: " ++ payload] will throw the MUL:Expression error.

<flow name="xmlToJsonFlow2" doc:id="efee0dcf-ceb5-42df-a73c-42b59e8e92fa" >
<http:listener doc:name="json2a" doc:id="5fa0ace7-5980-4caa-ae42-d84b12e53010" config-ref="HTTP_Listener_config" path="json2a"/>
<ee:transform doc:name="Transform Message" doc:id="17b369b9-b7a3-4cce-97df-0d7b4d02942a" >
<ee:message >
<ee:set-payload ><![CDATA[%dw 2.0
output application/json
var readXml = readUrl("classpath://Input/user2.xml", "application/xml")
---
{
FirstName: readXml.user.@FirstName,
LastName: readXml.user.LastName
}]]></ee:set-payload>
</ee:message>
</ee:transform>
<logger level="INFO" doc:name="Logger" doc:id="d4d565a0-5da6-4d89-ab3d-a582116c9562"
message='The payload is: #[payload]'/>
</flow>

the correct answer is B