**Core Concept**
The diagnostic criteria for major depressive disorder (MDD) are outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and include a range of symptoms that must be present for at least two weeks to meet the diagnostic threshold. These symptoms can be categorized into emotional, cognitive, and physical manifestations.

**Why the Correct Answer is Right**
Major depressive disorder is characterized by a combination of emotional symptoms, such as persistent feelings of sadness, hopelessness, and loss of interest in activities, as well as cognitive symptoms, such as indecisiveness, guilt, and worthlessness. Physical symptoms, such as changes in appetite and sleep patterns, are also common. However, not all symptoms listed in the options are included in the diagnostic criteria for MDD. Indecisiveness (Option A) is a cognitive symptom that can be present in MDD. Insomnia (Option B) is a physical symptom that can also be present. Therefore, the correct answer is that none of the options (D) are symptoms that are specifically excluded from the diagnostic criteria for MDD.

**Why Each Wrong Option is Incorrect**
**Option A:** Indecisiveness is indeed a symptom of major depressive disorder, as it falls under the category of cognitive symptoms.
**Option B:** Insomnia is also a symptom of major depressive disorder, as it falls under the category of physical symptoms.
**Option C:** Poor concentration is a cognitive symptom that can be present in major depressive disorder, as individuals with MDD may experience difficulty with decision-making and problem-solving.

**Clinical Pearl / High-Yield Fact**
It's essential to note that not all individuals with major depressive disorder will exhibit all the symptoms listed in the diagnostic criteria. A diagnosis of MDD is made when at least five symptoms are present, including either depressed mood or loss of interest in activities, for at least two weeks.

✓ Correct Answer: D. None of the above