Final answer:
The value of n in a paired differences test is the number of data pairs, which means the correct answer is B. The number of data pairs. Here, n is used to calculate the degrees of freedom for the hypothesis test as n - 1.
Step-by-step explanation:
When conducting a paired differences test, the value of n is the number of data pairs. This means the correct option is B. The number of data pairs. In the context of paired sample or matched-pair hypothesis testing, the calculation of differences between the pairs is crucial. Each pair consists of two measurements that are then subtracted to determine their difference. These differences make up the sample data set for the hypothesis test. When calculating the test statistic, such as a Student's t-score, this number of differences (n) is used to determine the degrees of freedom, which is n - 1. Therefore, with paired samples, each pair is considered as a single data value for the purpose of calculating n.