Final answer:
The correct CPT code for an established patient's office visit with a problem-focused history and exam, and straightforward MDM is 99212.
Step-by-step explanation:
The question pertains to the correct coding for an office visit for an established patient with a problem-focused history and exam, and straightforward Medical Decision Making (MDM). The correct code for this scenario is 99212. Code 99213 would not be appropriate as it corresponds to a visit that involves an expanded problem-focused history and examination, with low complexity MDM. Code 99211 is typically used for visits that don't require the presence of a physician or other qualified health care professional. Lastly, code 99201 would be incorrect as it is used for new patients, not established ones.