Answer:
a) combines the classical experimental design with the posttest-only control group design
Explanation:
The Solomon four group test, is a standard pretest- posttest two group design that focuses on the posttest control design. The various combinations of
tested and untested groups have helped with the treatment and control of the groups; and have allowed researchers to ensure that confounding variables and extraneous factors haven't influenced the results. The Solomon four group design is one of the benchmarks for sociological and educational research, and combats most of the internal and external validity issues in lesser designs.
