The circles whose equations are x² + y² + c² = 2ax and x² + y² + c² – 2by = 0 will touch one another externally if
(1) 1/b² + 1/c² = 1/a²
(2) 1/c² + 1/a² = 1/b²
(3) 1/a² + 1/c² = 1/c²
(4) None of these