If the equation of the locus of a point equidistant from the point (a₁, b₁) and (a₂, b₂) is (a₁ − a₂)x +(b₁ − b₂)y + c + 0, then the value of c is
A. a₁² − a₂² + b₁² − b₂²
B. √a₁² + b₁² − a₂² − b₂²
C. 1/2(a₂² + b₂² − a₁² − b₁²)
D. 1/2(a₁² + a₂² + b₁² + b₂²)