Answer:
B. an opal brooch
Explanation:
The altruism sees Sherlock Holmes endeavoring to restore a cap and goose lost by somebody on Christmas Day, yet the story at that point manages the robbery of a valuable stone, the Blue Carbuncle.
The ability of Holmes is shown in the analyst finding much about the proprietor of the cap and the goose basically from looking at the battered cap; however, the unraveling of the missing stone has substantially more to do with legwork than deduction.
