设总体为其样本，则服从分布（）.

• A.<img src="http://timg.fentiku.com/javaimportItems/e01c6f3ea2cc4e7daa7f73d03fef654d/images/1a788.png"><br/>
• B.<img src="http://timg.fentiku.com/javaimportItems/e01c6f3ea2cc4e7daa7f73d03fef654d/images/1ab1e.png"><br/>
• C.<img src="http://timg.fentiku.com/javaimportItems/e01c6f3ea2cc4e7daa7f73d03fef654d/images/1ae1b.png"><br/>
• D.<img src="http://timg.fentiku.com/javaimportItems/e01c6f3ea2cc4e7daa7f73d03fef654d/images/1b11c.png"><br/>

正确答案：B