Which of the following describes something that is "impervious"?

The term "impervious" refers to something that is unable to be affected by external factors or influences. This word is often used to describe materials that do not allow substances such as water or air to pass through them, as well as individuals or entities that are immune to external pressures or changes. Therefore, the choice describing an entity that is "unable to be affected by" aligns perfectly with this definition.

In contrast, the other options describe characteristics that are contrary to being impervious. For example, saying something is "capable of being influenced" suggests it can be changed or affected, which directly opposes the meaning of being impervious. Similarly, "easily penetrable" indicates that something can be easily influenced or accessed, again contradicting the idea of being impervious. Lastly, stating something is "affected by external forces" clearly implies that it is influenced by outside factors, which is the opposite of being impervious. Thus, the choice of being "unable to be affected by" is the only option that accurately reflects the meaning of the word.