Option D: 3 is the slope of the diagonal GE
Explanation:
Given that EFGH is a square drawn on a coordinate plane.
Diagonal FH is on the line 
We need to determine the slope of the diagonal GE.
Since, EFGH is a square and FH and GE are diagonals of the square.
The diagonals FH and GE are perpendicular to each other.
Thus, the slope of GE can be determined using the formula,

where
is the slope of FH and
is the slope of GE
From the line
, the slope is given by

Let us substitute the slope
in the formula, we get,

Multiplying both sides by
, we have,

Thus, the slope of the diagonal GE is 3
Therefore, Option D is the correct answer.