We're having a hard time selecting anything, because
you won't let us see what the options are.
Any option that looks like
x = K y
or
y = K x
or
A x = K y
or
A y = K x
or
A x - K y = 0
or
A y - K x = 0
is a proportional relationship between 'x' and 'y'.
The 'A' and 'K' can be any number except zero.
