**Core Concept**
Ectopic pregnancy is a life-threatening condition where the fertilized ovum implants outside the uterus, often in the fallopian tube. Medical treatment aims to prevent rupture and preserve the fallopian tube. hCG levels are a crucial factor in determining the appropriateness of medical treatment.

**Why the Correct Answer is Right**
The hCG level threshold for medical treatment of ectopic pregnancy is crucial because it reflects the likelihood of successful treatment and the risk of rupture. Medical treatment is generally offered to patients with hCG levels less than 1500-2000 IU/L. This is because hCG levels below this threshold are associated with a higher likelihood of successful treatment and a lower risk of rupture. The initial treatment aims to reduce hCG levels by inducing a medical abortion, thereby preventing further ectopic pregnancy growth and reducing the risk of rupture.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option may be tempting due to the lower hCG level, but it is too low for medical treatment to be effective. hCG levels below 100 IU/L are often associated with a very low likelihood of successful treatment.

**Option B:**
This option is slightly higher than the correct threshold but may still be associated with a higher risk of rupture. Medical treatment may still be offered in this scenario, but the risks and benefits should be carefully weighed.

**Option C:**
This option is too high, and medical treatment may not be effective in this scenario. hCG levels above 3000 IU/L are often associated with a higher risk of rupture and a lower likelihood of successful medical treatment.

**Clinical Pearl / High-Yield Fact**
In patients with ectopic pregnancy, the initial hCG level is a crucial factor in determining the likelihood of successful medical treatment. A level less than 1500-2000 IU/L is generally considered a good indicator for medical treatment, but the decision should be made on a case-by-case basis.

**Correct Answer:** **1500**.