The green parallelogram is a dilation of the black parallelogram. What is the scale factor of the dilation? A) 1/3
B) 1/2
C) 2
D) 3

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Explanation:

"The green parallelogram is a dilation of the black parallelogram"

This tells us that the preimage is the black parallelogram and the image is the green one.

In short, the mapping is

The image is smaller than the preimage (green is smaller than black), indicating the scale factor is some value of k such that 0 < k < 1. We can rule out choices C and D because of this.

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Measuring along the top, we can see that the black parallelogram goes from x = -6 to x = 8. Check out the image shown below where I've marked your given diagram, adding on helpful lines to show this going on.

The number-line distance from x = -6 to x = 8 is 14 units, so the top side of the black parallelogram is 14 units long.

The corresponding top side of the green parallelogram is 7 units long (because it spans from x = -3 and x = 4; as shown in blue in the figure below).

Divide the image length over its corresponding preimage length to get the scale factor.

scale factor = (image length)/(preimage length)

scale factor = 7/14

scale factor = 1/2

which points to choice B as our final answer.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.