We are given that:
\[
\frac{1}{1 - \tan x} = \frac{3 + \sqrt{3}}{2}
\]
Step 1: Simplifying the equation
Rearrange the equation to express \( 1 - \tan x \) as:
\[
1 - \tan x = \frac{2}{3 + \sqrt{3}}
\]
Now, rationalize the denominator by multiplying the numerator and denominator by \( 3 - \sqrt{3} \):
\[
1 - \tan x = \frac{2}{3 + \sqrt{3}} \times \frac{3 - \sqrt{3}}{3 - \sqrt{3}} = \frac{2(3 - \sqrt{3})}{(3 + \sqrt{3})(3 - \sqrt{3})}
\]
Simplifying the denominator using the difference of squares formula:
\[
(3 + \sqrt{3})(3 - \sqrt{3}) = 9 - 3 = 6
\]
Thus:
\[
1 - \tan x = \frac{2(3 - \sqrt{3})}{6} = \frac{3 - \sqrt{3}}{3}
\]
Step 2: Solving for \( \tan x \)
Now, solve for \( \tan x \):
\[
\tan x = 1 - \frac{3 - \sqrt{3}}{3} = \frac{3}{3} - \frac{3 - \sqrt{3}}{3} = \frac{\sqrt{3}}{3}
\]
Thus:
\[
\tan x = \frac{1}{\sqrt{3}}
\]
Step 3: Finding the value of \( x \)
We know that:
\[
\tan \frac{\pi}{6} = \frac{1}{\sqrt{3}}
\]
Thus:
\[
x = \frac{\pi}{6}
\]
Thus, the correct answer is option (C), \( x = \frac{\pi}{6} \).