The OED is not just a very large dictionary: it is also a historical dictionary, the most complete record of the English language ever assembled. It traces a word from its beginnings (which may be in Old or Middle English) to the present, showing the varied and changing ways in which it has been used and illustrating the changes with quotations which add to the historical and linguistic record. This can mean that the first sense shown is long obsolete, and that the modern use falls much later in the entry.
I believe that both are complete sentences.
I believe it might be B. Problem
