From inside your course, select Course Admin the QUIZZES.
Scroll down to the quiz you want to review. Select the drop down arrow (chevron) next to the name of the quiz. Select Statistics.
Select the third tab, labeled Question Details. Each questions is then displayed with the number of students who answered each multiple choice option and the corresponding percentage.
In the example below, each bar graph represents a multiple choice option. Ten students answered option D and that was 62.5% of quiz-takers. If the correct answer to this question was supposed to be A or B, then you might want to consider why most of the students answered incorrectly.
You can also export this information to an Excel file, by selecting the EXPORT TO EXCEL button near the top of the tabbed screen.