A researcher taking a dynamic-systems approach to motor development would be MOST likely to examine the impact of on the development of crawling.

multiple variables

Explanation:

Multiple variables entails that there may be more than one dependent variable and/or independent variable.

Such always comes to play out if you are conducting an experiment with multiple stages or sets of procedures.

In such type of experiments, there may be more than one set of measurements with different variables.

9) a & b

10) true.

11) false.

12) false.

13) true.

14) false.

15) true.

16) true.

don't worry, i'm here to you with your struggles!

good luck!

i am pretty sure it is d.