An argument is invalid if and only if (points : 1) its reasoning is strong and its premises are true. it is possible for all of its premises to be true and the conclusion false. it is fallacious. it has a false premise

An argument is invalid if and only if it is fallacious, it has a false premise.

This is something that many people struggle with - giving a good argument, as there are many cognitive biases together with argumentative flaws that riddle people who are trying to give an argument and debate. 

The answer is a abab okok9k9l9k9o9o