A research study was conducted that consisted of interviewing 12 women who had recently given birth on their experiences of the care that they received while in the hospital. This is known as what type of research study?

A research study was conducted that consisted of interviewing 12 women who had recently given birth on their experiences of the care that they received while in the hospital. This is known as what type of research study?
a. case study
b. A qualitative study
c. A quantitative study
d. A mixed design