Disagreement is one of the values of democracy, which can be fun in some argues and debates, but usually leads to finding a solution of public importance. Disagreement arises as a suppression of attitudes on many important issues, with valid arguments and reasons. They do not always see the same solution on a matter, and all parties and their interests and motives should be agreed upon. Therefore, reasonable people, because of their different views and attitudes, will not always agree on what is best for the public interest.
The answer is: b.