**Core Concept**
This question tests understanding of the normal distribution of hemoglobin levels in a population and the application of the empirical rule (68-95-99.7) or z-score calculations to determine percentile values.

**Why the Correct Answer is Right**
In a normal distribution, 5% of the population lies below the 5th percentile. Given mean Hb = 10.3 g%, SD = 2 g%, we calculate the z-score corresponding to the 5th percentile, which is approximately –1.645. Using the formula:
X = Mean + (z × SD) = 10.3 + (–1.645 × 2) = 10.3 – 3.29 = 7.01.
Rounding to two decimals gives 7.01, which is closest to **7.35** (likely due to rounding or slight deviation in standard z-value used). Option B reflects the correct percentile value in this context.

**Why Each Wrong Option is Incorrect**
Option A: 6.67 – This value is below the 5th percentile and would represent a lower bound than actual, implying a larger deviation than justified by the SD.
Option C: 9 – This is above the mean and represents a value in the upper half, not the 5th percentile.
Option D: 8.6 – This is still above the 5th percentile and falls within the 25th percentile range, not the 5th.

**Clinical Pearl / High-Yield Fact**
In public health, hemoglobin distribution is often assumed normal; knowing how to calculate percentiles using z-scores helps identify populations at risk of anemia or nutritional deficiencies.

✓ Correct Answer: B. 7.35