The hospital quality assurance administrator wanted to conduct a research study to see if there would be a difference in satisfaction ratings between patients who were in single-occupant rooms compared to patients in shared rooms (rooms with a roommate). Satisfaction was measured on the 1-5 'Patient Satisfaction Index' with '1' representing the lowest and '5' the highest satisfaction rating. The results indicated higher satisfaction from patients in single-occupant rooms compared to patients in shared rooms, p = 0.02 . From the information given in the above statement: What statistical test was used for this study?

A. None of the answers given here are correct

B. Mann-Whitney U test

C. Repeated measure ANOVA

D. Independent t-test, also called the Student's t-test