By definition, the Standard Deviation is a dispersion measure. Therefore, it indicates the variability in a set of data or in a population. The higher the variability, the larger the Standard Deviation.
You know that NBA players have all a similar height. It is usually greater than:
In the case of the general population, there is more variability in their heights.
Therefore, you can conclude that the Standard Deviation is larger for the general population.
Hence, the answer is: The general population, because there is more variability in their heights.