There are 25 men and 20 women who belong to a club. An executive panel consisting of a president, vice president, secretary, and treasurer is being chosen
a) In how many ways could the executive panel be chosen with no restrictions? [A, 1m]
b) In how many ways could the executive panel be chosen if it must include at least one woman and one man? [A, 2m]
c) In how many ways could the executive panel be chosen if the president and vice president must have different genders [A, 2m]