This class represents a question on the Morse Fall Scale Assessment Instrument. This abstract class exists primarily to re-define the generic AssessmentInstrument.item.question property to the MorseFallScale.item.question. In other words, of all the possible questions on all the possible assessment instruments, we are explicitly identifying the six Morse Fall Scale questions. Note that because this class is abstract, implementers would likely not instantiate this class, but rather the six concrete sub classes.