Of the Following, Which Is a Quantitative Research Problem

Of the following, which is a quantitative research problem?

A) The purpose of this study is to examine how teacher's should help students during office hours.
B) The purpose of the study is to explore the experiences of students who seek help from faculty during office hours.
C) The purpose of this study is to compare the grades of students who go to office hours and those who do not.
D) The purpose of this study is to suggest how many office hours faculty should hold each week.