What fallacy attempts to discredit another person's conclusions by showing how their particular situation in life makes them unable to render a credible verdict on a given issue?

The correct answer is: Argumentum ad hominem.

Explanation:

Argumentum ad hominem is type of fallacy that consists in assuming an affirmation or proposition is false by discrediting or attacking the person that is emitting said argument, it does not focus on the argument per se but solely in the character, motive or attribute of the person related with the argument. Therefore in this case the fallacy referred is the Ad hominem because showing a particular situation in order to argument the inability to render a credible veredict on a given issue is an attack not to the argument but to the person.