What are the advantages of single-case research?

What will be an ideal response?

(a) Single-case research provides a wealth of detail, much more than for a group design, where in depth information would be too much to evaluate.
(b) Single-case research is also good for studying rare phenomena.
(c) Single-case research can be used for creating and testing research hypotheses.
(d) Single-case research is useful for studying clinical interventions on single people whose specific symptoms are unique.