If the chords of contacts of the tangents from the points

$\left(x_1, y_1\right)\text{ and }\left(x_2, y_2\right)\text{ to the hyperbola }2x^2-3y^2=6$

are at right angle, then $4x_1{x}_2+9y_1{y}_2$ is equal to

• A

  –1

• B

  0 

• C

  6 

• D

  –12