Check all the statements that are true: a. if a procedure can be broken down into a sequence of two tasks, and if there are n ways to do the first task, and m ways to do the second task, then there are nm ways to do the procedure. b. if n and r are nonnegative integers and ≤ then c(n, r) = p(n, r)/r! . c. there are functions from a set of n elements to a set of m elements. d. a surjective function from a set of n elements to a set of n elements is automatically injective . e. if n is a nonnegative integer, then the sum of all the c(n, k) is f. if s is a finite set, s has 2|s| subsets. g. a finite set with n members has c(n, k) subsets of size k. h. if a task can be done either in one of n ways or in one of m ways, then there are n+m ways to do the task. i. there are n! bijections from a set with n elements to itself. j. the cardinality of a cartesian product of sets is the product of the cardinalities of the individual sets. k. combinations c(n, r) are symmetrical in r with respect to the point =. l. if there are 2n+1 objects in n boxes, then at least one box must contain at least 3 objects. m. if n is a nonnegative integer, then the alternating sums of all the c(n, k) are 0. n. if n and k are positive integers with ≥ then c(n+1,k) = c(n, k) + c(n, k+1). o. an injective function from a set of n elements to a set of n elements is automatically surjective.