Which of the following represents the orthogonal trajectories of the system of coaxial circles x² y² +2λx+c=0?
a) x² + y² + 2λy+c=0
b) x² - y² + 2λy+c=0
c) x² - y² - 2λy+c=0
d) x² - y² + 2λy+c=0