Of the following, which describes a likely causal---comparative study?

Of the following, which describes a likely causal---comparative study?

a.      Typical management procedures used by experienced teachers in a child- care setting.

b.      Relationship between teacher job satisfaction and years of teaching

c.      Differences in problem solving performance between children randomly assigned to a computer training program and those who were not given the same exposure

d.      Differences in acclimation to high school between children from small and large middle schools