The correct option is A orthocentre
The lines y=x and √3y+x=0 are inclined at 450 and 1500, respectively, with the positive direction of x-axis.
So, the angle between the two lines is an obtuse angle.
Therefore, orthocentre lies outside the given triangle, whereas incentre and centroid lie within the triangle (In any triangle, the centroid and the incentre lie within the triangle).