The sets of ordered pairs below represent relations.

I {(0, 0), (1, 1), (2, 2), (3, 3), (4, 4)}
II {(1, 2), (2, 1), (1, 3), (0, 1), (3, 1)}
III {(0, 2), (1, 2), (2, 4), (3, 4), (3, 6)}
IV {(1, 6), (2, 6), (3, 6), (4, 6), (5, 6)}
Which of these sets are also functions?

I only

I and IV

II and III

II, III, and IV

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?