=>

We have
\(x=\frac{1}{2+\sqrt{3}}\)
\(x=\frac{2-\sqrt{3}}{\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)}\) (multiplying by the conjugate)
\(x=\frac{2-\sqrt{3}}{4-3}\) (foiling the denominator)
\(x=2-\sqrt{3}\) (simplifying)
\(x-2=-\sqrt{3}\) (subtracting 2 from both sides)
\(\left(x-2\right)^2=\left(-\sqrt{3}\right)^2\) (squaring both sides)
\(x^2-4x+4=3\) (simplifying)
\(x^2-4x=-1\) (subtracting 4 from both sides)

Therefore, the answer is B.
Answer: B