A researcher wants to test whether displaying a new slogan $($the independent variable$)$ will increase sign$-$ups on a website newsletter $($the dependent variable$).$ The researcher gathers a sample of $200$ participants. In the control condition,$100$ participants see the current business slogan on the website. In the experiment condition, $100$ participants see the new slogan on the website. Then the researcher compares the percentage of newsletter sign$-$ups between the two groups using statistical analysis. The researcher uses a $\_\_\_\_\_\_\_\_\_\_\_$design.

a$.$

Between subject design

b$.$

Single subject design

c$.$

Longitudinal design

d$.$

Within subject design