Which of the following medications is primarily used for managing anxiety and is classified as Schedule IV?

Diazepam is primarily used for managing anxiety and is classified as a Schedule IV controlled substance. This classification indicates that it has a lower potential for abuse relative to Schedule I, II, and III drugs, but it still requires regulation due to its potential for dependence and misuse. Diazepam belongs to the benzodiazepine class of medications, which are commonly prescribed to treat various anxiety disorders, as well as for their muscle relaxant, anticonvulsant, and sedative properties.

In contrast, pentazocine is primarily used as an analgesic (pain reliever) and is classified differently due to its potential for abuse. Kayexalate is not used for anxiety; rather, it is utilized to treat high potassium levels in the blood. Hydrocodone is an opioid used primarily for pain management and is classified as a Schedule II controlled substance, reflecting its higher potential for abuse and dependence compared to Schedule IV medications. Thus, diazepam stands out as the correct choice for its specific use in anxiety management and its classification.