Final answer:
Factors like reliable evidence and logical conclusions strengthen an argument, while omitting relevant information weakens it.
Step-by-step explanation:
Among the factors that can strengthen an argument, ensuring that evidence is reliable, that conclusions logically follow from the premises, and that counterarguments are effectively addressed, are all aspects that contribute positively. However, one choice actually weakens the argument: when relevant information is omitted from the argument. Leaving out relevant information can lead to an incomplete or skewed understanding of the issue, thus undermining the argument's validity and persuasiveness.