**Core Concept**
Hysterosalpingography (HSG) is a radiologic procedure used to evaluate the uterine cavity and fallopian tubes. It involves the insertion of a contrast medium into the uterus through the cervix, followed by X-ray imaging to visualize the uterine cavity and fallopian tubes.

**Why the Correct Answer is Right**
HSG is typically performed during the secretory phase of the menstrual cycle, when the endometrium is thinner and less likely to interfere with the imaging. This is usually around days 21-28 of a 28-day menstrual cycle, after ovulation has occurred. The secretory phase is chosen to minimize the risk of ectopic pregnancy and to allow for better visualization of the uterine cavity and fallopian tubes.

**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because HSG is not typically performed during the follicular phase, when the endometrium is thicker and more likely to interfere with imaging.
**Option B:** This is incorrect because HSG is not typically performed during menstruation, when the endometrium is shedding and the risk of bleeding is higher.
**Option C:** This is incorrect because HSG is not typically performed during pregnancy, when the risk of ectopic pregnancy and other complications is higher.

**Clinical Pearl / High-Yield Fact**
It's essential to note that HSG should be performed during the secretory phase to minimize the risk of complications and to ensure accurate imaging of the uterine cavity and fallopian tubes.

**Correct Answer:** D.