**Core Concept**
The question is testing knowledge of the reservoirs of hospital-acquired infections, specifically focusing on the carriage of haemolytic Streptococcus in healthcare workers. This concept is crucial in understanding the epidemiology of nosocomial infections and implementing infection control measures.

**Why the Correct Answer is Right**
Haemolytic Streptococcus, particularly Group A beta-haemolytic Streptococcus (GABHS), can be carried in the throat of healthy individuals. This commensal carriage is a significant reservoir for the spread of infection in healthcare settings. The bacteria can colonize the anterior nares, throat, and skin of healthcare workers, who may then transmit the infection to vulnerable patients, such as those undergoing surgery or with compromised immune systems. The pharynx is a common site for GABHS carriage, and healthcare workers may inadvertently spread the bacteria through close contact or poor hand hygiene.

**Why Each Wrong Option is Incorrect**
* **Option A:** Nasal carriage is also a common site for GABHS, but the question specifically asks about haemolytic Streptococcus, which is more commonly associated with throat carriage.
* **Option B:** Skin carriage is a possibility, but the question is more focused on the specific site of carriage, which is the throat.
* **Option D:** There is no specific evidence to suggest that haemolytic Streptococcus is commonly carried in the gastrointestinal tract.

**Clinical Pearl / High-Yield Fact**
Healthcare workers should be aware of the importance of proper hand hygiene and respiratory etiquette to prevent the spread of haemolytic Streptococcus and other pathogens. This includes covering the mouth and nose when coughing or sneezing, and thoroughly washing hands with soap and water after interacting with patients.

**Correct Answer:** .