the mathematics test level 3 question 16 states that : let a,b,c be complex numbers that represent the two vertices of a triangle, then which of the following statements must be true? A:a+b+c is the orthocentre of the triangle B: a+b+c/3 is the centroid of the triangle C: a+b+c/2 is the centre of the nine-point circle of the triangle D: The product of abc is a real number the choice of answers are: a. A b. B c. C d. D But A,B and C are all correct. If there any typo of the question?