Consider the Diagram Below $$\begin{array} { l l l } \mathrm { R } & & \mathrm { O } _ { 1 } \\\mathrm { R } & \mathrm { X } & \mathrm { O } _ { 2 }\end{array}$$

Multiple Choice

Consider the diagram below. Which experimental design is depicted?
$$\begin{array} { l l l } \mathrm { R } & & \mathrm { O } _ { 1 } \\\mathrm { R } & \mathrm { X } & \mathrm { O } _ { 2 }\end{array}$$

A) the posttest-only control-group design
B) the pretest-posttest control-group design
C) the Solomon four-group design
D) the interrupted time-series design