Quadrilateral wxyz is on a coordinate plane. segment yz is on the line x+y=7, and segment xw is on the line x+y=3. which statement proves how segments yz and xw are related?
a. they have slopes that are opposite reciprocals of 1 and -1 and are therefore perpendicular
b. they have the same slope of 1 and are therefore parallel
c. they have slopes that are opposite reciprocals of 0 and undefined and are therefore perpendicular
d. they have the same slope of -1 and are therefore parallel