Which of the following statements defines a function? choose the correct answer below. a. a function is a set of ordered pairs in which none of the first components in the ordered pairs are negative. b. a function is a set of ordered pairs where all the first components in the ordered pairs have the same value. c. a function is a set of ordered pairs in which each second component in the ordered pairs corresponds to exactly one first component. d. a function is a set of ordered pairs in which each first component in the ordered pairs corresponds to exactly one second component.