请教prep 08中一个they指代的问题

qqqlyx

The first detailed study of magpie attacks in Australia indicates that by the time they had reached adulthood, 98 percent of men and 75 percent of women born in the country have been attacked by the birds

A.by the time they had reached adulthood, 98 percent of men and 75 percent of women born in the country have been attacked by the birds

B.by the time they reach adulthood, 98 percent of men and 75 percent of women, who were born in the country, had been attacked by the birds
C.by the time they reached adulthood, 98 percent of men and 75 percent of women born in the country had been attacked by the birds
D.98 percent of men and 75 percent of women that were born in the country were attacked by the birds by the time they reach adulthood
E.98 percent of men and 75 percent of women who were born in the country, by the time they reached adulthood had been attacked by the birds

我想请教一下的是 正确选项C 中 that的指代，  that不是完全指代嘛？ 为什么指代的是men and women而不是98% men and 75% women呢？

谢谢！