7. (15 points) Six Avengers, five X-Men, and four Guardians of the Galaxy are in the running for a promotion to a new super-group. This super-group will consist of five members - not every group needs to be represented.
(a) In how many ways can the super-group be chosen?
(b) What is the probability that the super-group will leave out the Guardians of the Galaxy?
(c) What is the probability that the super-group is made of members from a single group?