**Core Concept**
The presence of Wolffian and Mullerian ducts is a critical aspect of embryological development, particularly in the formation of the reproductive system. The **Wolffian ducts** are responsible for the development of male reproductive structures, while the **Mullerian ducts** give rise to female reproductive structures.

**Why the Correct Answer is Right**
In normal male development, the **SRY gene** triggers the production of **Mullerian-inhibiting substance (MIS)**, which causes the regression of Mullerian ducts, while **testosterone** promotes the development of Wolffian ducts. In females, the absence of MIS allows Mullerian ducts to develop into female reproductive structures, and the lack of testosterone means Wolffian ducts regress.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not apply to the context of the question, which is about the presence of both ducts.
**Option B:** Similarly, this option does not fit the scenario of having both types of ducts present.
**Option C:** This option is also incorrect as it doesn't align with the typical development where both ducts are present.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that disorders of sex development (DSD) can result from abnormalities in the formation or function of these ducts, leading to variations in genital development.

**Correct Answer:** D. True Hermaphroditism