**Core Concept**
The diagnosis of tuberculosis (TB) is crucial for its management and control. According to the World Health Organization (WHO), the detection of TB involves specific criteria. The **bacillus** must be identified through various methods.

**Why the Correct Answer is Right**
The correct answer is based on the WHO's definition of a TB case, which often involves the identification of **Mycobacterium tuberculosis** through **smear microscopy** or **culture**. The WHO criteria for detecting TB include symptoms such as cough, fever, and weight loss, along with laboratory confirmation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a method for detecting TB.
**Option B:** This option is also incorrect as it is not a recognized method for TB detection by WHO.
**Option C:** Similarly, this option does not align with WHO's criteria for TB detection.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the WHO's End TB Strategy aims to reduce TB incidence and deaths, with accurate detection being crucial.

**Correct Answer:** D.