Answer:
 (c)  8x^2 -32x +32, repeated root is x=2.
Step-by-step explanation:
A quadratic with repeated roots will be a multiple of a perfect square trinomial. The form of it will be ...
 a(x -b)² = ax² -2abx +ab² = a(x² -2bx +b²)
Dividing by the leading coefficient will leave a monic quadratic whose constant is a (positive) perfect square, and whose linear term has a coefficient that is double the root of the constant.
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Dividing by the leading coefficient gives ...
 x^2 -18x -81 . . . . . a negative constant
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Dividing by the leading coefficient gives ...
 x^2 -2x +3 . . . . . . constant is not a perfect square
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Dividing by the leading coefficient gives ...
 x^2 -4x +4 = (x -2)^2 . . . . . has a repeated root of x=2
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Dividing by the leading coefficient gives ...
 x^2 -1.2x -0.36 . . . . . . a negative constant
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The x-coefficient is not 2 times the root of the constant.
 14 = √196 ≠2√196
