In the equation y = kx, the slope of the line is represented by the constant
a.) x
b.) k
c.) y
d.) k+x

K is the constant of proportionality also the same as slope.
You can see the commonality in the equations
y = kx
y = mx + b
The difference is that is a direct proportion the line will always go through the origin so the b will be zero.
The answer is B.

This question doesn’t make any sense