Cross-sectional research designs provide information about age in development between different age groups. Longitudinal research designs provide information concerning in behavior over time.
A. changes; age differences
B. changes; age changes,
C. differences; age differences,
D. differences; changes,

D. differences; changes,                                                      

Explanation:

Cross-sectional research design: In psychological or scientific research, the term cross-sectional research is determined as an observational research design whereby an investigator or experimenter tends to measure and analyze the exposure and outcome of specific research participants or subjects at the "same time.

Longitudinal research design: In scientific or psychological research, the term "longitudinal research design" is also referred to as panel study or longitudinal survey and is described as a research design in which repeat observations of same research participants is being done over a long or short period in time.

In the question above, the correct answer is option D.

there are indirect ways of affecting state laws   by with holding funding's. and that's why we have a 55mph speed on the high way with a design of 70mph speed.