What does "untenable" imply about a position or argument?

The term "untenable" is used to describe a position or argument that cannot be maintained or defended, indicating that it lacks the necessary support or justification. When something is characterized as untenable, it suggests that the reasoning or evidence backing it is so weak or flawed that it cannot withstand critical scrutiny or opposition. This makes it impossible to uphold the stance convincingly.

In contrast, the other choices imply that a position or argument can be defended or is accepted, which directly contradicts the essence of "untenable." A position that is easily defendable or universally accepted does not align with the inability to maintain or support it. Similarly, the idea that it can be logically sustained is at odds with being untenable, as logical sustenance implies that there is sufficient grounding to hold the argument. Therefore, the choice that accurately captures the meaning of "untenable" is that it refers to something that cannot be held or defended, embodying the core concept of being impossible to maintain.