**Core Concept**
The patient is presenting with symptoms of pulmonary tuberculosis (TB), as indicated by positive sputum smear for Acid-Fast Bacilli (AFB) and haemoptysis. The patient has already received a 3-week course of antitubercular therapy (RHZE), which consists of Rifampicin (R), Isoniazid (H), Pyrazinamide (Z), and Ethambutol (E).

**Why the Correct Answer is Right**
The patient's treatment should be categorized as "Failure" due to the presence of symptoms and positive sputum smear after 3 weeks of antitubercular therapy. This indicates that the causative Mycobacterium tuberculosis is resistant to the first-line drugs, and the patient requires a thorough evaluation and modification of their treatment regimen. The patient should undergo a detailed investigation, including chest X-ray, sputum culture, and drug susceptibility testing, to determine the extent of drug resistance.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as the patient's symptoms and sputum smear positivity indicate treatment failure.
**Option B:** The patient is not a treatment "default" since they had been on treatment for 3 weeks and then discontinued, which is a different scenario.
**Option C:** While the patient does require further evaluation, the term "relapse" implies that the patient had completed a full course of treatment and then relapsed, which is not the case here.
**Option D:** The patient's symptoms and sputum smear positivity indicate treatment failure, not "pulmonary TB not requiring treatment".

**Clinical Pearl / High-Yield Fact**
When a patient presents with symptoms of pulmonary TB and has received previous treatment, it is essential to thoroughly evaluate the patient's response to treatment and modify the regimen accordingly. A thorough investigation, including drug susceptibility testing, is crucial to determine the extent of drug resistance and guide further treatment.

**Correct Answer: A. Failure. The patient's symptoms and positive sputum smear after 3 weeks of antitubercular therapy indicate treatment failure, requiring further evaluation and modification of the treatment regimen.**