In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom or phrase a bone of contention.

Introduction / Context:
This is an idiom based vocabulary question. The phrase a bone of contention is a common English idiom used in everyday speech, newspapers, and examinations. The task is to select the option that best captures its figurative meaning rather than its literal picture of a bone. Understanding idioms is important for reading comprehension because writers often use them to summarise complex relationships in a single vivid phrase.

Given Data / Assumptions:

• The idiom given is a bone of contention.
• Four paraphrased meanings are offered as options.
• The context is general English, so the idiom is used in its standard figurative sense.
• We assume no special technical or legal usage.
• We must choose the meaning that most people would understand when they hear this idiom.

Concept / Approach:
Historically, the expression comes from the image of two dogs fighting over a bone. The bone represents the thing that causes the fight. In modern usage, a bone of contention is anything that repeatedly causes argument, dispute, or disagreement between people, groups, or nations. Therefore the best paraphrase is an issue over which there is continuing disagreement. The key ideas are issue and continuing disagreement, which fully reflect the sense of the idiom.

Step-by-Step Solution:
Step 1: Ignore the literal meaning of bone and focus on how the idiom is used in sentences such as The boundary line has long been a bone of contention between the two villages. Step 2: Notice that in such sentences the phrase points to the cause of a quarrel or dispute. Step 3: Read all the options and identify which one mentions disagreement or conflict. Step 4: Option B states An issue over which there is continuing disagreement. This directly matches the quarrel based sense. Step 5: Confirm that the other options refer to agreement, property, or happiness, which are unrelated to the core idea of contention.

Verification / Alternative check:
You can test the meaning by substituting the idiom with option B in sample sentences. For example, The new tax law has become a bone of contention between the citizens and the government can be rewritten as The new tax law has become an issue over which there is continuing disagreement between the citizens and the government. The sentence still makes perfect sense, which shows that option B successfully captures the idiom. The same substitution fails with the other options, proving that they are incorrect.

Why Other Options Are Wrong:
The only part to which two arguing parties agree: This describes a point of agreement, while contention is about disagreement, so this is almost the opposite meaning. A very expensive inherited property: This focuses on money and inheritance and fails to mention disagreement or conflict. It has no link to contention. To be happy with only a few things: This describes contentment, not contention. The similar sound between content and contention might confuse some learners, but the meanings are very different.

Common Pitfalls:
A frequent problem is confusion between words with similar spelling but different meanings. Content means satisfied, whereas contention means dispute. The idiom a bone of contention is based on contention, not content. Another pitfall is to take idioms literally and imagine only physical bones rather than the figurative message. For exam success, regular reading of editorials and articles is helpful, because idioms like this appear often in discussions of politics, economics, and social issues.

Final Answer:
A bone of contention means an issue over which there is continuing disagreement.