Pascal's formula says that if n and r are positive integers with r ≤ n, then _______.
a. The formula for the combination of n objects taken r at a time is given by C(n, r) = n! / (r! * (n-r)!)
b. The formula for the permutation of n objects taken r at a time is given by P(n, r) = n! / (n-r)!
c. The formula for the binomial coefficient is given by C(n, r) = n! / (r! * (n-r)!)
d. The formula for the number of ways to choose r elements from a set of n distinct elements is given by C(n, r) = n! / (r! * (n-r)!)