**Core Concept**
The coefficient of correlation is a statistical measure that quantifies the relationship between two variables, in this case, weight and height. It ranges from -1 (perfect negative correlation) to 1 (perfect positive correlation), with 0 indicating no correlation.

**Why the Correct Answer is Right**
When calculating the net correlation coefficient, we need to consider the individual correlations between weight and height in each sample. Since all 4 samples have the same coefficient of correlation of 0.6, we can assume that the correlations are consistent across the samples. However, the net correlation coefficient depends on the relationship between the samples themselves. In this case, since the samples are independent and have the same correlation coefficient, the net correlation coefficient will be the same as the individual correlation coefficient, which is 0.6.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it suggests that the net correlation coefficient would be 0, which is only true if the individual correlations are random or have opposite directions.
* **Option B:** This option is incorrect because it suggests that the net correlation coefficient would be greater than the individual correlation coefficient, which is not possible in this scenario.
* **Option C:** This option is incorrect because it suggests that the net correlation coefficient would be less than the individual correlation coefficient, which is not possible in this scenario.

**Clinical Pearl / High-Yield Fact**
When dealing with multiple samples and correlation coefficients, it's essential to consider the relationship between the samples themselves, as this can affect the net correlation coefficient.

**Correct Answer: . 0.6**