These two sources are actually quite similar. In order to see how this is so, I suggest that you try to briefly summarize each one. You will see that the main points being made are very much the same in both sources.
In Source C, we see an interview with a woman about what factors she considers when deciding whether to have another child. She says that the bonuses given by the government do matter. However, she also says that raising a child takes a great deal of time, particularly with the difficulty of the educational system. She says that parents need more flexibility in their work schedules so that they can take time off to do things that their children need. Thus, she is saying that financial bonuses help convince her to have more children, but that flexible work hours are also important.
In Source D, we have a sociologist’s take on how Singapore could encourage people to have more children. To see her main points, simply look at her first and last sentences. She says that financial bonuses are useful, but that what parents really need is greater flexibility in their work schedules. They need employers to be willing to let them off of work when necessary.
Looking at these two summaries, we can see that they are saying essentially the same things. The similarity between them is that they both think that the “baby bonus” scheme is helpful but that flexible work hours are more important.