A group of college DJs surveyed students to find out what music to plan for their upcoming parties. Thirty percent of the students preferred dubstep, 25% of the students liked trance music, and 20% wanted to hear only house music. Fifteen percent of the respondents selected both dubstep and trance.

The proportion of students that like trance music but not dubstep is.

a) 20% .
b) 5% .
c) 10% .
d) 15%