A study of 30 fathers were asked " What is the highest level of education you have completed ?" 5 completed only elementary school; 15 completed elementary and high school; 7 completed elementary , high school and college , and 3 completed elementary , high school, college and graduate school. What is the cumulative percentage of fathers who completed college?

a.) 13%

b.) 36%

c.) 23%

d.) 33%