**Core Concept**
Angular pregnancy, also known as a cornual pregnancy, is a rare form of intrauterine pregnancy where the implantation occurs in the interstitial portion of the fallopian tube, which is the portion that passes through the uterine wall. This type of pregnancy is distinct from other forms of ectopic pregnancies that occur in the interstitial or isthmic portions of the fallopian tube.

**Why the Correct Answer is Right**
Intrauterine pregnancy refers to the normal implantation of a fertilized ovum in the uterine cavity, which is the primary location for embryonic development. Angular or cornual pregnancy is a specific type of intrauterine pregnancy that occurs in the interstitial portion of the fallopian tube, as opposed to the more common utero-placental implantation in the uterine cavity. This distinction is critical for proper diagnosis and management.

**Why Each Wrong Option is Incorrect**
**Option A:** Ectopic pregnancy of interstitial part of FT is incorrect because while it does occur in the interstitial portion of the fallopian tube, it is not an intrauterine pregnancy but rather an ectopic one.
**Option C:** Heterotopic pregnancy is incorrect because it refers to a pregnancy with both intrauterine and ectopic components, whereas angular pregnancy refers specifically to an intrauterine implantation in the interstitial portion of the fallopian tube.

**Clinical Pearl / High-Yield Fact**
Angular or cornual pregnancies are often associated with an increased risk of miscarriage, preterm labor, and uterine rupture due to the abnormal implantation site and potential compromise of the uterine wall.

**✓ Correct Answer:** B. Intrauterine pregnancy