A. This is an inference. The statement has a referenced argument, but data are not cited.
B. This is an inference. Data are included to present projections, not direct observations.
C. This is an assumption. There are no references to percentages to clarify the point, nor are there data to support a conclusion that there is now or ever was a clear demarcation between middle and old age.
D. This is an inference because projections are educated guesses, but not observations.
E. This is an observation. Percentages of older Asians living with their children are declining drastically.