**Core Concept**
Postpartum depression (PPD) is a mood disorder that affects women after childbirth, with symptoms ranging from mild to severe. The pathophysiology of PPD involves hormonal changes, including fluctuations in estrogen and progesterone levels, as well as neurobiological factors such as alterations in neurotransmitter systems like serotonin.

**Why the Correct Answer is Right**
The medication approved for postpartum depression is a selective serotonin reuptake inhibitor (SSRI), which increases the levels of serotonin in the synaptic cleft, thereby enhancing its neurotransmission. This mechanism is thought to be critical in alleviating depressive symptoms in PPD. The specific drug in question works by inhibiting the reuptake of serotonin by the presynaptic neuron, allowing more serotonin to be available for binding to postsynaptic receptors.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while it may be used in the treatment of depression, it is not specifically approved for postpartum depression.
**Option B:** This option is incorrect because it is not an SSRI and does not have a mechanism of action that is typical for antidepressants.
**Option C:** This option is incorrect because it is a non-selective serotonin reuptake inhibitor, which can have more side effects and is not the preferred choice for treating postpartum depression.

**Clinical Pearl / High-Yield Fact**
It's essential to note that SSRIs are generally considered safe during breastfeeding, but their use should be carefully evaluated on a case-by-case basis to minimize potential risks to the infant.

**Correct Answer:** C.