Okay, let's tackle this question about major depressive disorder. First, I need to figure out what the core concept is. The question is asking which statement is true about major depressive disorder (MDD). The options aren't given, but since the correct answer is marked as C, I should focus on what makes option C correct.

The core concept here is likely the diagnostic criteria for MDD according to DSM-5. The key points include symptoms like depressed mood, anhedonia, weight changes, sleep disturbances, psychomotor changes, fatigue, feelings of worthlessness, and suicidal ideation. Also, the duration is at least two weeks, and it must cause significant impairment.

Now, why is the correct answer right? If option C mentions the required number of symptoms (at least five) and the duration, that's correct. For example, if C states that a person must have five or more symptoms for two weeks, that aligns with DSM-5 criteria. The explanation should highlight that the presence of five symptoms for two weeks is necessary for diagnosis, along with the impact on daily functioning.

For the wrong options, let's consider common distractors. Option A might incorrectly state that only three symptoms are needed, which is wrong because it's five. Option B could mention a duration of one week, which is too short. Option D might suggest that anhedonia is not a key symptom, but it's one of the two core symptoms (along with depressed mood). Each of these would be incorrect for specific reasons related to the diagnostic criteria.

The clinical pearl here is to remember the DSM-5 criteria: five symptoms over two weeks, including depressed mood or anhedonia. A mnemonic like "SIGECAP" might help, but the key is knowing the exact number and duration. Also, differentiating MDD from other disorders like dysthymia (which is chronic but less severe) is important.

Putting it all together, the correct answer is C because it correctly addresses the required symptoms and duration. The other options fail to meet these criteria. The clinical takeaway is the diagnostic threshold and the necessity of impairment.

**Core Concept**
Major depressive disorder (MDD) is diagnosed using DSM-5 criteria requiring **at least five symptoms** (including depressed mood or anhedonia) for **≥2 weeks**, causing significant functional impairment. Key symptoms include weight/appetite changes, sleep disturbances, psychomotor agitation/retardation, fatigue, guilt, and suicidal ideation.

**Why the Correct Answer is Right**
If the correct option states that MDD requires **five or more symptoms** for **two weeks**, this aligns with DSM-5 guidelines. Two core symptoms (depressed mood or anhedonia) must be present, along with ≥4 additional symptoms. Duration is critical to differentiate MDD from adjustment disorders or transient sadness.

**Why Each Wrong Option is Incorrect**
**Option A:** Suggests a shorter duration (e.g., 1 week) — DSM-5 mandates ≥2 weeks for diagnosis.
**Option B:** Claims only three symptoms are required — MDD requires ≥5 symptoms, with two being core.
**Option D:** States anhedonia is not a diagnostic criterion — anhedonia is one of the *two* essential symptoms.

**Clinical Pearl / High-Yield Fact**
Remember **SIGECAP** as a mnemonic for key depressive

✓ Correct Answer: D. All