Answer;
D. Counterexample
One way to show that a statement is not a good definition is to find a counterexample.
Explanation;
A counterexample is a special type of example that disproves a statement or proposition.
Conditional Statement is a logical statement that has a hypothesis and a conclusion and for it to be true, it must always be true.
A counterexample is at least one example that proves a conditional statement false or disproves it.