I believe its B. Stratified because the owner had to speak to ten individuals, meaning he divided it into smaller groups.
Each year the boat is worth 100-12 = 88% ( or 0.88) of the year before
after 12 years the boat is worth 12050 * 0.88^9 = $3813.56
Assuming that the triangle is isoceles, the answer should be 30.
The hypotenuse length is √(4*4 + 3*3) = 5 (not √7 I suppose)
The area is base*half height = 4*3/2 = 6.
In short, I don't think complex numbers really interfere here.
