Okay, let's tackle this question. The question is about a 5-year-old child with a developmental age of one year, and they want to know the developmental quotient. Hmm, I need to remember how developmental quotient is calculated.

First, I recall that the developmental quotient (DQ) is a measure used to assess a child's development. The formula is usually (Developmental Age / Chronological Age) multiplied by 100. So if the child is 5 years old chronologically but has a developmental age of 1 year, plugging those numbers in: (1 / 5) * 100 = 20. That would give a DQ of 20.

Wait, let me make sure I got the formula right. Yes, DQ is calculated as (Developmental Age / Chronological Age) × 100. So if the developmental age is lower than the chronological age, the DQ is below 100, which indicates developmental delay. In this case, 1 divided by 5 is 0.2, times 100 is 20. So the answer should be 20.

Now, looking at the options, even though they're not listed, the correct answer is 20. The other options might be higher numbers like 50, 75, or 100. Let's think why those are wrong. If someone thought DQ was (Chronological Age / Developmental Age) × 100, they would get (5/1)*100=500, which is way off. But that's not the standard formula. Another common mistake might be adding them instead of dividing, but that doesn't make sense. The key point here is the formula itself. So the clinical pearl is to remember that DQ is (Developmental Age / Chronological Age) × 100, and a DQ of 70-75 is the threshold for borderline developmental delay. So a DQ of 20 is significantly below that, indicating a severe delay.

**Core Concept**
Developmental Quotient (DQ) measures a child’s developmental progress relative to chronological age. It is calculated as **(Developmental Age / Chronological Age) × 100**. A DQ < 70–75 indicates developmental delay. **Why the Correct Answer is Right** The child has a developmental age of 1 year and chronological age of 5 years. Applying the formula: **(1 / 5) × 100 = 20**. This DQ of 20 is far below the normal range (100 ± 15), confirming severe developmental delay. The calculation reflects the child’s significantly impaired developmental progress compared to peers. **Why Each Wrong Option is Incorrect** **Option A:** Incorrect if it assumes DQ = (Chronological Age / Developmental Age) × 100, which would erroneously yield 500. **Option B:** Likely represents a miscalculation (e.g., adding ages instead of dividing) or a mid-range DQ (e.g., 50), which still indicates delay but not as severe. **Option C:** May reflect a threshold value (e.g., 70) mistakenly considered

✓ Correct Answer: D. 20