The correct answer to this open question is the following.
Although you forgot to include the options for this question, we can say the following.
The thought that an effective leader has a high-quality relationship with each follower, allowing out-group members to be part of the larger group is the Leader-Member Exchange Theory.
This theory was developed at the beginning of the 1970s. It focuses on how leaders establish relationships with the members of their teams in order to help them grow inside the company or, on the other hand, how managers can put a hold on employees' careers.
Under the principles of this theory, the leader and the employee pass through three stages. 1.- Role-Taking. 2.- Role Making. 3.- Routinization.
UNder any leadership style, the leader has to lead by example. It has to be a great communicator, a good listener. Have a set of skills and abilities to perform under pressure. The leader has to make the toughest decisions. And of course, he has to hire the best individuals to form a true team.