Which statement defines a function correctly

A function gives for each element of the domain only one element of the range.

Step-by-step explanation:

We have to choose from the statements in the options that define a function correctly.

From my point of view the statement that a function gives for each element of the domain only one element of the range,  defines a function properly.

Geometrically it represents that if we draw a vertical line in the graph of the function that intersects the graph at more than one points then this is not a function, this is only a relation. (Answer)

b.an increase in a causes b to decrease

6, 10

9, -13

12, -21

18, -23

step-by-step explanation:

you just add 6 to the x-coordinate and subtract 10 from the y-coordinate.