**Core Concept**
Ectopic pregnancy is a life-threatening condition where a fertilized egg implants outside the uterus, most commonly in the fallopian tube. The risk of ectopic pregnancy is influenced by various factors, including the use of assisted reproductive technology, previous ectopic pregnancy, and pelvic infections.

**Why the Correct Answer is Right**
The least risk of ectopic pregnancy is associated with **natural conception** in a woman without any history of pelvic surgery, ectopic pregnancy, or pelvic inflammatory disease. Natural conception allows for a normal anatomical environment with minimal disruption to the fallopian tubes, reducing the likelihood of an ectopic implantation. In contrast, assisted reproductive technologies like IVF and ICSI can increase the risk of ectopic pregnancy due to the manipulation of the gametes and embryos.

**Why Each Wrong Option is Incorrect**
* **Option A:** Women with a history of previous ectopic pregnancy have a significantly increased risk of subsequent ectopic pregnancies, often cited as high as 10-15%. This is due to the underlying anatomical or physiological factors that predisposed the initial ectopic pregnancy.
* **Option B:** Pelvic surgery, including tubal ligation or salpingectomy, can increase the risk of ectopic pregnancy as it may damage the fallopian tubes or disrupt their normal function.
* **Option C:** Pelvic inflammatory disease (PID) caused by sexually transmitted infections can lead to scarring and adhesions in the fallopian tubes, increasing the risk of ectopic pregnancy.

**Clinical Pearl / High-Yield Fact**
The "Rule of 10s" for ectopic pregnancy risk is a useful mnemonic: 10% risk with a previous ectopic pregnancy, 10-15% risk with a history of pelvic surgery, and 10-15% risk with pelvic inflammatory disease.

**Correct Answer:** D. Natural conception in a woman without a history of pelvic surgery, ectopic pregnancy, or pelvic inflammatory disease.