Senator: Between 1950 and present, the number of women diagnosed with

Between 1950 and present, the number of women diagnosed with PP depression each year has increased by a factor of ten. (So in 1950, if 200 women had PP depression, now 2000 do)
We must improve our systems for supporting women after childbirth to stem this increase in the number of new mothers experiencing postpartum depression.

What will call this argument into question?
There are various ways:
- If we can say that number of new mothers has increased by a factor of 20, then PP depression seems to have reduced percentage wise.
- If we can say that it existed in similar numbers before but was just not diagnosed before, that will call our argument into question.
- If we can say that it existed in similar numbers but was misdiagnosed as some other disease, that will serve the purpose too.
etc

A. The amount of spending on women’s health has increased since 1950.

Irrelevant

B. Rates of postpartum depression are not included in official government statistics.

Irrelevant

C. The minimum threshold of symptoms women experience before they can be diagnosed has increased since 1950.

This should have led to fewer cases, not more.

D. Until 1970, most doctors were not specific in their diagnoses but instead grouped all types of depression together.

So PP depression was not diagnosed as such by MOST doctors earlier. It was just called depression. Then it is possible that 2000 women had PP depression in 1950 also but for 1800 of them, it was just called depression. Only very few doctors identified PP depression and hence we got the number fo 200 in 1950.
This weakens our argument.

E. It is likely that cases of postpartum depression are underreported in Heranita.

This means that there are even more cases than 2000 and perhaps there were more than 200 in 1950. Doesn't help.

Answer (D)