A longitudinal study of the relationship between loss of mobility in the elderly and subsequent development of depression was performed. 300 patients were followed for a period of 12 months. At a significance level of p < 0.05, the null hypothesis is which of the following? A. When compared to adults who do not lose mobility, there is a difference in the incidence of depression in adults who lose mobility B. When compared to adults without loss of mobility, there is no difference in the incidence of depression in adults with mobility loss C. When compared to normal adults, there is a difference in the incidence of depression in adults with a history of loss of mobility 5% of the time D. When compared to normal adults, there is no difference in the incidence of depression in adults with a history of mobility loss 5% of the time 41