In the following question on English idioms, choose the alternative which best expresses the meaning of the expression Take up the hatchet, which uses war imagery.

Introduction / Context:
This idiom question tests your understanding of the expression Take up the hatchet. The phrase uses the image of a hatchet, a small axe used historically as a weapon. In idiomatic English, it refers not to carpentry or general work but to the idea of preparing for conflict or war. Recognising such war related idioms is important when reading historical accounts and figurative political commentary.

Given Data / Assumptions:

• Idiom given: Take up the hatchet.
• Options describe formal behaviour, pursuing a chance, being trapped, and preparing for war.
• Only one option correctly reflects the historical and idiomatic sense of the phrase.
• The question assumes familiarity with similar idioms like bury the hatchet, which has the opposite meaning of making peace.

Concept / Approach:
In many cultures, taking up weapons symbolises beginning or renewing hostilities. To take up the hatchet means to prepare for war or to start fighting again. It is frequently contrasted with bury the hatchet, which means to end a conflict. The correct answer will therefore mention preparation for war or direct engagement in conflict, not just formal behaviour or taking opportunities.

Step-by-Step Solution:
Step 1: Recall that a hatchet is a small axe that can be used as a weapon. Step 2: Understand that take up suggests picking up the weapon, implying readiness to fight. Step 3: Examine option a, behave formally. This is unrelated to fighting or weapons. Step 4: Examine option b, pursue a chance. This speaks about opportunity, not conflict. Step 5: Examine option c, be caught in a trap, which describes a state of helplessness, not conscious preparation for war. Step 6: Examine option d, prepare for or go to war, which matches the weapon based imagery and the idiomatic meaning. Step 7: Choose option d as the best expression of the idiom.

Verification / Alternative check:
Consider a sentence such as After years of peace, the tribes took up the hatchet once again. The meaning clearly is that they resumed fighting, not that they started behaving formally or chasing chances. If we substitute prepare for war, the sentence retains its sense. In contrast, inserting pursue a chance would make no logical sense in this context. This confirms that the idiom refers specifically to war or conflict.

Why Other Options Are Wrong:
Behave formally: This may involve manners or dress, not weapons or conflict.
Pursue a chance: Focuses on opportunity and ambition rather than hostility.
Be caught in a trap: Describes being stuck or deceived, which is not implied by taking up a weapon.

Common Pitfalls:
Because many exams also test the idiom bury the hatchet, which means to make peace, learners sometimes mix up the two and think that both are about ending fights. It is important to note that take up the hatchet is the opposite and signals starting or renewing hostility. Remembering this pair as a contrast, with bury meaning peace and take up meaning war, will help you avoid mistakes and quickly identify the correct answer in exam conditions.

Final Answer:
The idiom Take up the hatchet means prepare for or go to war, so option d is correct.