**Core Concept**
The correct insertion of an Intrauterine Contraceptive Device (IUCD) depends on various factors to avoid complications and ensure effective contraception. The ideal candidate for IUCD insertion should have an empty uterine cavity, a cervical os that allows the device to be easily inserted, and a stable medical condition.

**Why the Correct Answer is Right**
In cases where the uterus has a cavity deformity, such as a fibroid or a previous uterine surgery like a cesarean section, the IUCD may not be inserted. This is because the device may not be able to be placed correctly, leading to potential complications like perforation of the uterus or embedment of the device. Additionally, the presence of a fibroid may also interfere with the effectiveness of the IUCD.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because there is no specific contraindication for IUCD insertion in nulliparous women.

**Option B:** This option is incorrect because IUCD insertion is not contraindicated in women with a previous history of pelvic inflammatory disease (PID).

**Option C:** This option is incorrect because the presence of a uterine fibroid or a cavity deformity is not the only contraindication for IUCD insertion.

**Clinical Pearl / High-Yield Fact**
It is essential to ensure that the uterine cavity is evaluated before IUCD insertion, especially in women with a history of uterine surgery or fibroids, to minimize the risk of complications.

**Correct Answer:** C.