**Core Concept**
Brucella is a gram-negative, facultative intracellular bacterium that causes brucellosis, a zoonotic disease affecting humans and animals. Brucella species exhibit capnophilic growth, require a humid environment, and can be transmitted through direct contact with infected animals or contaminated products.

**Why the Correct Answer is Right**
Option D mentions the use of 2-Mercaptoethanol (2-ME) for detecting IgA antibodies against Brucella. However, 2-ME is specifically used to detect IgM antibodies against Brucella, not IgA. This is because IgM is more sensitive and specific for acute infections, whereas IgA is more indicative of chronic infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Brucella is indeed capnophilic, meaning it requires a humid environment with a specific CO2 level to grow. However, the term "capnophilic" refers to a different bacterium, Neisseria, which requires increased CO2 levels for optimal growth.

**Option B:** Transmission of Brucella by aerosol is extremely rare and typically occurs in laboratory settings or when handling contaminated products. However, the primary mode of transmission is through direct contact with infected animals or their products.

**Option C:** Pasteurization is an effective method for destroying Brucella bacteria. This is because Brucella is highly susceptible to heat and can be easily killed by temperatures above 60°C.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that Brucella species exhibit slow growth, requiring extended incubation periods for culture isolation. This is why serological tests and molecular diagnostics are often used in conjunction with culture to confirm Brucella infections.

**Correct Answer:** ✓ Correct Answer: D. 2ME is used to detect IgA