To determine whether a graph of a relation is also a function, shayla declares that the y-axis is a vertical line and counts the number of times that the graph intersects the y-axis. if the graph has exactly one y-intercept, shayla concludes that the graph shows a function. in all other cases, she declares that it is not a function.

is shayla applying the vertical line test correctly?

options:
no, because the y-axis is a horizontal line.
no, because using the y-axis tests only whether x = 0 is mapped to multiple values.
yes, because multiple y-intercepts represent multiple x-values being mapped to y = 0.
yes, because the y-axis represents all vertical lines of the x-values.