陈向东里的一道题引出的问题

The ratio of dicorces to marriages has increased since 1940. Therefore, there must be a greater proportion of children living with only natural parent than there was in 1940.
Which of the following, if ture, most strongly weakens the inference drawn above?
A The number of marriages entered into by women twenty-five to thirty-five years old has decreased since 1940.
B When there is a divorce , children are often given the option of deciding which parent they want to live with.
C Since 1940 the average number of children in a family has remained approximately steady and has not been subject to wide fluctuations.
D Before 1940 relatively few children whose parents both died were adopted into single-parent families.
E The proportion of children who must be raised by one parent because the other has died has decreased since 1940 as a result of medical advances.