Which of the following situations involve a permutation?
select all the correct answers.

a) determining how many different ways 7 runners can be assigned lanes on a track for a race

b) determining how many 5-letter passwords can be made using the word "graph."

c) determining how many different groups of 10 students can be chosen to go on a field trip from a group of 25 students

d) determining how many different ways to choose 3 employees from a group of 9 employees.

e) determining how many different seating charts can be made placing 6 people around a table

f) determining how many different ways 4 cashiers can be chosen to work from a group of 6 cashiers.