A team of psychologists studied the effect of multitasking on the completion of cognitive tasks. A group of 40 women participated in the study. Each woman owned a smartphone equipped with the same type of keyboard. The women typed a text passage on the phone twice, one time while sitting in a quiet room (a single task) and the other time while walking (a multitask). The order of the single task and the multitask was randomly determined for each woman. The psychologists recorded the time it took each woman to type the text for both tasks. If the conditions of inference are met, which of the following tests is most appropriate to analyze the data?
a. A two-sample t-test for a difference between means
b. A matched-pairs t-test for a mean difference
c. A one-sample z-test for a proportion
d. A two-sample z-test for a difference between proportions
e. A chi-square test of independence