Final answer:
The constant of variation k for the direct variation given by the equation 4x = -y is -4.
Step-by-step explanation:
The question asks to find the constant of variation k for the direct variation represented by the equation 4x = -y. In direct variation, the equation is written in the form y = kx, where k is the constant of variation. To find k, we rearrange the original equation to this form:
y = -4x
Thus, the constant of variation k is -4, which matches option D.