Quote:
“Because I made a blunder, my dear Watson—which is, I am afraid, a more common occurrence than any one would think who only knew me through your memoirs. The fact is that I could not believe it possible that the most remarkable horse in England could long remain concealed, especially in so sparsely inhabited a place as the north of Dartmoor. From hour to hour yesterday I expected to hear that he had been found, and that his abductor was the murderer of John Straker. When, however, another morning had come, and I found that beyond the arrest of young Fitzroy Simpson nothing had been done, I felt that it was time for me to take action. Yet in some ways I feel that yesterday has not been wasted.”
Question:
"A more common occurence than any one would think" means:
A. something more common than everyone thought happened
or
B. something very rare happened
According to the context i guess the answer should be B. But i do feel confused with such expression.