Vocabulary (adjective for trustworthiness): choose the most appropriate word to complete the sentence. He is quite __________; you can never count on him in matters of secrecy.

Introduction / Context:
This question checks whether you can choose the precise adjective that matches the idea of someone you cannot trust in confidential matters. The clue is in the phrase \"you can never count on him in matters of secrecy\", which points directly to reliability and trustworthiness, not to justice, comfort, or efficiency.

Given Data / Assumptions:

• Sentence: He is quite __________; you can never count on him in matters of secrecy.
• Options: unjust, unbearable, inefficient, unreliable.
• The sentence emphasises the inability to count on him, particularly when secrecy is required.
• We assume his problem is that he does not keep secrets or cannot be trusted.

Concept / Approach:
The main clue is \"never count on him\". The verb \"count on\" means \"rely on\" or \"trust\" someone. Therefore, the missing adjective must describe a person who cannot be relied upon. Among the options, only \"unreliable\" directly expresses that idea. The other options refer to fairness, tolerance, or work performance, which do not fit the given context.

Step-by-Step Solution:
Step 1: Identify the key phrase: \"you can never count on him\". This is about reliability. Step 2: Test \"unjust\": This means \"not fair\" or \"not just\" in terms of moral or legal correctness. It does not relate to keeping secrets or being dependable. Step 3: Test \"unbearable\": This means \"very difficult to tolerate\" and usually applies to situations or people who are annoying, but not directly to whether you can rely on someone in secrecy. Step 4: Test \"inefficient\": This applies to someone who does not work effectively or wastes time or resources. It does not necessarily mean they cannot keep secrets. Step 5: Test \"unreliable\": This means that you cannot rely on the person; they do not consistently do what they are expected to do. This matches the description of someone you cannot count on.

Verification / Alternative check:
You can rephrase the sentence with synonyms: \"He is quite unreliable; you can never depend on him in matters of secrecy.\" This sounds natural and coherent. If you try the other words, the sentence becomes illogical: \"He is quite unjust\" or \"inefficient\" in context of secrecy does not make sense. This confirms that \"unreliable\" is the only correct choice.

Why Other Options Are Wrong:
Option \"unjust\": Refers to unfairness in behaviour or decision making, not to dependability in keeping secrets. Option \"unbearable\": Refers to someone or something that is too difficult to tolerate, often due to behaviour or conditions, but not to trust in confidential matters. Option \"inefficient\": Relates to poor performance or low productivity, not trustworthiness.

Common Pitfalls:
Learners sometimes choose adjectives based on general negativity rather than precise meaning. In exams, look for the part of the sentence that defines the specific type of problem. Here, \"never count on him\" clearly points to reliability, not just any negative quality.

Final Answer:
The complete sentence is: He is quite unreliable; you can never count on him in matters of secrecy. So, the correct option is unreliable.