Forty percent of the rats included in an experiment were male rats. If some of the rats died during the experiment and 30 percent of the rats that died were male rats, what was the ratio of the death rate among the male rats to the death rate among the female rats?

(A) 9/14
(B) 3/4
(C) 9/11
(D) 6/7
(E) 7/8

Please explain.