Final answer:
O 3. His patients stop coming to him because of his animals. Dr. Dolittle's problem in the passage is that his patients stop coming to him because of his animals, leading to a decline in his finances.
Step-by-step explanation:
The central problem faced by Dr. Dolittle in the passage from The Story of Doctor Dolittle by Hugh Lofting is that his patients stop visiting his practice due to the large number of animals he keeps in his home. This decline in his patient base causes Dr. Dolittle's financial situation to worsen, as highlighted by the various items he has to sell to support himself and his pets. Ultimately, the passage suggests that Dr. Dolittle values his animal companions more than his medical practice or financial stability.