**Core Concept**
Extraintestinal amoebiasis refers to the spread of Entamoeba histolytica infection beyond the gastrointestinal tract, involving various organs and tissues. This condition can occur due to the amoeba's ability to invade and cause damage to distant sites through the bloodstream.

**Why the Correct Answer is Right**
The liver is the most common site of extraintestinal amoebiasis, primarily due to the amoeba's hematogenous spread. When E. histolytica infects the intestine, it can invade the intestinal wall and gain access to the bloodstream. The liver, being a key organ for detoxification and filtration, is particularly susceptible to amoebic invasion. The amoeba can then cause liver abscesses, which can be life-threatening if left untreated.

**Why Each Wrong Option is Incorrect**
* **Option A:** Although the lungs can be involved in amoebiasis, they are not the most common site of extraintestinal infection.
* **Option B:** The spleen can be affected in cases of extraintestinal amoebiasis, but it is not the primary site.
* **Option C:** The skin can be involved in some cases of amoebiasis, but it is not the most common site of extraintestinal infection.

**Clinical Pearl / High-Yield Fact**
Extraintestinal amoebiasis can present with non-specific symptoms such as fever, weight loss, and abdominal pain, making it essential to consider this diagnosis in patients with unexplained systemic illness.

**Correct Answer: C. Liver.