**Core Concept**
The question is testing the timeline of fetal development, specifically the onset of auditory function. In utero, the fetus's auditory system matures, allowing it to perceive sound. This process is critical for the development of language and other cognitive skills.

**Why the Correct Answer is Right**
The fetus starts hearing around 24 weeks of gestation. This is when the cochlea, a spiral-shaped structure in the inner ear responsible for sound processing, begins to function. The auditory nerve, which transmits sound signals to the brain, also matures during this period. The fetal auditory system can detect sounds outside the womb, such as maternal voice and music, which can influence the fetus's brain development.

**Why Each Wrong Option is Incorrect**
**Option A:** The exact timeline of fetal hearing development is not around 16 weeks, as the fetal auditory system is still maturing at this stage.
**Option B:** The fetus does not start hearing around 28 weeks, as this is slightly later than the actual onset of auditory function.
**Option C:** The exact timeline of fetal hearing development is not around 20 weeks, as the fetal auditory system is still maturing at this stage.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that fetal exposure to sound, especially maternal voice and music, can have a lasting impact on the child's language development and cognitive skills. This highlights the importance of considering the auditory environment in utero.

**Correct Answer:** C. 24 weeks of gestation.