Answer:
D: There are a number of reasons why the birthrate in Japan is falling.
Step-by-step explanation:
Looking at the three points given, we can see that there is a trend.
In the first point, we learn that Japanese women are not marrying due to the traditional idea that marriage is more diplomatic than it is romantic, and we can infer that this will lead to a decline in the number of families started.
The second point is pretty cut and dry; raising a child is expensive, and that may seem unattractive to young people who'd otherwise be the ideal candidates to start a family.
The third point strengthens the message by pointing out that even if a family could afford to have children, it wouldn't be a very enjoyable experience. It can be inferred that the stresses of having a child discourage married couples in Japan from having multiple children.
All of these points together support answer choice D, as it is the only statement supported by all three points without any other outside information.