Explanation:

To settle a dispute, one needs to have a sound decision-making ability to be able to judge both the sides. Also, a judge is a free body to decide upon any issue.

'Know' is a verb which means to be aware of through observation, inquiry, or information. 'Tactics' refer to an action or strategy carefully planned to achieve a specific end.

A judge doesn't need tactics to make a judgment. 'Discretion' means the freedom to decide what should be done in a particular situation.

'Brains' refer to the intellectual capacity.

'Bias' means inclination or prejudice for or against one person or group, especially in a way considered to be unfair.

Hence option 3 is the correct response