Which of the following candidates are binary or unary operations on the given sets? For those that are not, where do they fail? a. x compositefunction y = greatest common multiple of x and y; S = N b. x compositefunction y = x + y; S = the set of Fibonacci numbers c. x # = the string that is the reverse of x; S = set of all finite-length strings of symbols from the set {p, q, r} d. x compositefunction y = x + y; S = R