An argument gives you the opportunity to a) show the weakness in someone's character b) encourage someone to take action c) promote someone's personal agenda d) prove someone's incorrect statements

D: prove someone's incorrect statements.

Explanation:

 An argument can be a situation in which two or more people disagree, but it is not necessary that people be angry, only a presentation of people's opinion or explanation of why they believe something should be done. It's a matter of rhetoric and logic. People use it to convince others to agree with what they say or defend. It´'s considered basic of critical thinking.