**Core Concept**
Ectopic pregnancy is a life-threatening condition where the fertilized ovum implants outside the uterus, most commonly in the fallopian tube. This condition is a leading cause of maternal mortality in the first trimester of pregnancy.

**Why the Correct Answer is Right**
The most common symptom of ectopic pregnancy is **abdominal pain**, which occurs due to the rupture of the fallopian tube or the growing embryo exerting pressure on surrounding structures. This pain can be sharp, stabbing, or dull and aching, and is often described as a sharp, stabbing pain on one side of the abdomen. The pain may be accompanied by other symptoms such as vaginal bleeding, nausea, and vomiting.

**Why Each Wrong Option is Incorrect**
**Option A:** **Dizziness** is not a common symptom of ectopic pregnancy. While some women may experience dizziness due to anemia or other factors, it is not a characteristic symptom of ectopic pregnancy.

**Option B:** **Frequent urination** is not typically associated with ectopic pregnancy. While some women may experience urinary frequency during pregnancy due to the growing uterus, it is not a common symptom of ectopic pregnancy.

**Option C:** **Shortness of breath** can occur in some cases of ectopic pregnancy, but it is not the most common symptom. Shortness of breath may occur if the ectopic pregnancy is large or if there is significant bleeding, but it is not as common as abdominal pain.

**Clinical Pearl / High-Yield Fact**
The "rhoGAM shot" is often given to prevent RhoD alloimmunization in Rh-negative women, but it is not effective in preventing the symptoms of ectopic pregnancy. **The most common symptom of ectopic pregnancy is abdominal pain**.

**Correct Answer:** C.