in the given triangle,
AB = BC = 6
As, the two sides are equal so, the given triangle is isosceles.
also, the angle < ABC = 120 degrees,
the area of the isosceles triangle is,
here a = length of two congruent sides,
theta = the angle between congruent sides.
put the values,
A = 1/2 x 6^2 x sin 120
thus, the correct answer is option D