A company that makes fleece clothing uses fleece produced from two farms, Northern Farm and Western Farm. Let the random variable X represent the weight of fleece produced by a sheep from Northern Farm. The distribution of X has mean 14.1 pounds and standard deviation 1.3 pounds. Let the random variable Y represent the weight of fleece produced by a sheep from Western Farm. The distribution of Y has mean 6.7 pounds and standard deviation 0.5 pound. Assume X and Y are independent. Let W equal the total weight of fleece from 10 randomly selected sheep from Northern Farm and 15 randomly selected sheep from Western Farm. Which of the following is the standard deviation, in pounds, of W? 
选项为:A:$$1.3+0.5$$  B:$\sqrt{1.3^{2}+0.5^{2}}$  C:$\sqrt{10(1.3)^{2}+15(0.5)^{2}}$  D:$\sqrt{10^{2}(1.3)^{2}+15^{2}(0.5)^{2}}$  E:$\sqrt{\dfrac{1.3^{2}}{10}+\dfrac{0.5^{2}}{15}}$  请回答其中一个选项.