Final answer:
Rating schemes can generate hard numbers to work with, but they do not necessarily provide a clear sense of risk relative to other options. They are not primarily used in marketing research. Rating schemes are not solely based on qualitative data and can be useful in risk assessment when used appropriately.
Step-by-step explanation:
Rating schemes can generate hard numbers to work with, but they do not necessarily provide a clear sense of risk relative to other options (option a). They are not primarily used in marketing research (option b). Rating schemes are not based on qualitative data only, but can incorporate both quantitative and qualitative data (option c). Lastly, rating schemes can be useful in risk assessment when used appropriately (option d is incorrect).