Solve $(3 + \sqrt{3})x + 2 = 5 + 3\sqrt{3}$:

Isolating $x$ gives $(3+\sqrt3)x = 3 + 3\sqrt3$; rationalizing by multiplying numerator and denominator by $(3-\sqrt3)$ yields $x = \dfrac{6\sqrt3}{6} = \sqrt3$, which checks: $(3+\sqrt3)\sqrt3 + 2 = 5 + 3\sqrt3$. (This is option b; the marked key c would require RHS $8 + 4\sqrt3$.)