## **Core Concept**
The question revolves around the side effects of antidepressants, specifically their impact on sexual function, including libido and erectile function. Antidepressants can have varying effects on sexual function, with some classes being more likely to cause sexual side effects than others.

## **Why the Correct Answer is Right**
Mirtazapine (option D) is known for having a favorable side effect profile regarding sexual function. It is a tetracyclic antidepressant that acts as a noradrenergic and specific serotonergic antidepressant (NaSSA). Mirtazapine has a lower risk of sexual side effects, such as decreased libido and erectile dysfunction, compared to selective serotonin reuptake inhibitors (SSRIs) and some other antidepressants. This makes it a suitable option for patients concerned about these side effects.

## **Why Each Wrong Option is Incorrect**
- **Option A:** SSRIs, such as fluoxetine, are well-known for their potential to cause sexual side effects, including decreased libido and erectile dysfunction. This is due to their mechanism of action, which involves the inhibition of serotonin reuptake, affecting various serotonin receptors that play a role in sexual function.
- **Option B:** Tricyclic antidepressants (TCAs) can also cause sexual side effects, although the profile may vary among different TCAs. They are not typically the first choice when trying to minimize sexual side effects.
- **Option C:** Monoamine oxidase inhibitors (MAOIs) have a different side effect profile and can have sexual side effects, though they are less commonly used today due to dietary restrictions and interactions.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while mirtazapine has a lower risk of sexual side effects, no antidepressant is completely free of these side effects, and individual responses can vary widely. When considering antidepressants and their sexual side effects, it's crucial to assess the patient's specific concerns and medical history.

## **Correct Answer:** D. Mirtazapine.