Answer:
B. If you plan to adopt a kitten, please bring a pet carrier.
(B) The walk around Saxe-Coburg Square
is the key event in story which leads to Holmes' solution of the case.
Well, it's not A. Mary did not let hm accept the disease.
It's not B-he told her about his mother (I think).
It's not D because she is brought to live there.
It's C because she doesn't let him accept his illness and ends up helping him.
