If \(a = \frac{{\sqrt 3 \; + \;1}}{{\sqrt 3 - 1}}and\;b = \frac{{\sqrt 3 - 1}}{{\sqrt 3 \; + \;1}}\) then a2 + ab + b2 = ____

• A. 15
• B. 14
• C. -15
• D. \(15 + 18\sqrt 3\)