Valerie's state passed a law mandating a free public pre$-$kindergarten education for three$-$ and four$-$year$-$old children, although school enrollment is not mandatory until age five, with kindergarten. She is tracking the school$-$readiness and reading$-$readiness scores of all children starting kindergarten to see how the children who are enrolled in the pre$-$K program do in comparison to those of similar background who do not attend. Valerie is conducting

applied research

implementation research

basic research

policy research