**Core Concept**
Gastrojejernostomy surgery, a type of gastrointestinal procedure, involves creating a new connection between the stomach and the jejunum (a part of the small intestine). This surgery is typically performed to alleviate conditions such as gastric outlet obstruction or to facilitate easier passage of food. The classification of surgical procedures is based on the risk of microbial contamination, which in turn determines the need for prophylactic antibiotics and other infection control measures.

**Why the Correct Answer is Right**
Gastrojejernostomy surgery is classified as clean-contaminated surgery because it involves entering the gastrointestinal tract with a surgical incision, thereby introducing the risk of microbial contamination. However, this risk is considered moderate, as the operation does not involve entering the lumen of the gastrointestinal tract under uncontrolled conditions. The presence of a controlled opening, such as an incision in the stomach or jejunum, allows for the use of prophylactic antibiotics and other infection control measures to minimize the risk of surgical site infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Clean surgery refers to procedures that do not involve entering the respiratory, gastrointestinal, genitourinary, or oropharyngeal tracts. Gastrojejernostomy surgery clearly involves entering the gastrointestinal tract, making it an incorrect classification.
**Option B:** Contaminated surgery involves procedures where the respiratory, gastrointestinal, genitourinary, or oropharyngeal tracts are entered under uncontrolled conditions, such as with a perforation or a tumor. Gastrojejernostomy surgery is not performed under uncontrolled conditions, making it an incorrect classification.
**Option D:** Dirty surgery refers to procedures where there is significant contamination with feces or other infectious material. Gastrojejernostomy surgery does not involve significant contamination with feces or other infectious material, making it an incorrect classification.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the classification of surgical procedures is not solely based on the type of operation but also on the surgeon's judgment regarding the risk of microbial contamination. Surgeons must exercise caution and consider the specific circumstances of each procedure when determining the appropriate classification.

**✓ Correct Answer: C. Clean contaminated surgery**