Answer:
The most accurate answer is *They fear that if they give a positive reference for someone who doesn't work out in a new job, they may be sued by that person's new employer.
Explanation:
Giving a reference of an employees character, professional and ethical behavior, productivity and integrity is a great responsibility and not just a mere simple act.
this is mainly because the references are a main way to assess the suitability of hiring an employee and if we give an incorrect reference, the other firm might rely on it and hire an ineffective employee.