I think it D) A glossary lists the meanings of difficult words in a text.
Explanation:
A glossary also known as a vocabulary or clavis, is an alphabetical list of terms in a particular domain of knowledge with the definitions for those terms. Traditionally, a glossary appears at the end of a book and includes terms within that book that are either newly introduced, uncommon, or specialized. While glossaries are most commonly associated with non-fiction books, in some cases, fiction novels may come with a glossary for unfamiliar terms.
D. A glossary lists the meaning of difficult text.
Explanation:
This is the actual definition of glossary, "an alphabetical list of terms or words found in or relating to a specific subject, text, or dialect, with explanations; a brief dictionary." And this definition matches closely to D.
It can dry on you and your equipment leaving crystals that might not do you much harm (dry skin, uncomfortable itchy feeling) but will definitely start degrading your equipment