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

Multiple Choice

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

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