In the following question, out of the four alternatives, select the option which best expresses the meaning of the idiom or phrase “gnash your teeth”.

Introduction / Context:
This idiom question asks about the meaning of the phrase “gnash your teeth”. Idioms often come from physical actions that symbolise strong emotions. Here, gnashing the teeth is a powerful image connected to intense negative feelings. Understanding this idiom helps you interpret emotional scenes in literature, news reports and conversations.

Given Data / Assumptions:

• Idiom: gnash your teeth.
• Options: express rage, brush your teeth, laugh hysterically, take a big bite.
• Literal image: grinding or clenching the teeth together, often with force.
• Common emotional link: anger, frustration, pain or despair.

Concept / Approach:
To gnash one's teeth literally means to grind or strike the teeth together, usually as a sign of extreme anger, pain or frustration. In idiomatic usage, it refers mainly to showing rage or strong annoyance, sometimes powerless rage when you cannot change a situation. It has nothing to do with brushing teeth, laughing or eating. Thus, “express rage” best captures the emotional meaning of the idiom in normal usage.

Step-by-Step Solution:
Recall the physical action: gnashing implies forceful grinding of the teeth.Associate this with common situations: people clench or grind their teeth when angry or deeply upset.Option Express rage: directly matches this emotional reaction.Option Brush your teeth: refers to cleaning and has no connection with anger.Option Laugh hysterically: describes extreme laughter, the opposite of anger or frustration.Option Take a big bite: relates to eating, again unrelated to emotional rage.Therefore, “Express rage” is the correct meaning of the idiom.

Verification / Alternative check:
Use the idiom in a sentence: “The fans gnashed their teeth when their team lost in the final minute.” Here, the fans are not brushing their teeth or laughing; they are showing intense anger and frustration. If we rephrase it as “The fans expressed rage when their team lost,” the meaning remains the same. That confirms that expressing rage is the intended sense.

Why Other Options Are Wrong:
Brush your teeth is a purely literal daily activity and never used as an idiom for emotions. Laugh hysterically suggests extreme amusement or joy, which clashes completely with the negative, angry tone of gnashing one's teeth. Take a big bite may involve teeth physically, but in English it does not describe an emotional reaction. The presence of teeth in the phrase is a distraction; the correct cue is the violent grinding action, not ordinary use in eating or cleaning.

Common Pitfalls:
Some learners focus too literally on the word teeth and choose options related to eating or brushing. However, idioms must be interpreted as whole expressions. To avoid mistakes, always ask: in what emotional situation would someone gnash their teeth? It is when they are furious, frustrated or in intense pain. Remembering this connection between gnashing and rage will help you answer similar idiom questions confidently in the exam.

Final Answer:
The idiom “gnash your teeth” means to express rage or intense anger.