Which of the following is (are) true?  I. The sampling distribution of a sample mean will be approximately normally distributed for sufficiently large samples, regarless of the shape of the original population.  II. The sampling distribution of a sample mean will be normally distributed if the population from which the samples are drawn is normal.  III. $\sigma\_{\bar{x}} = \frac{\sigma}{\sqrt{n}}$ if N$\geq$10n. 
选项为:A:I  B:II  C:III  D:I, II  E:I, II, III  请回答其中一个选项.