In the following sentence, choose the most appropriate expression to complete the blank so that the sentence is grammatically correct and natural in standard English: You are ____ common sense.

Introduction / Context:
This English grammar question tests knowledge of standard collocations in modern usage, particularly the correct prepositional phrase after the verb be when describing the absence of something. Learners often confuse phrases like lacking of, lacking in, and devoid of. Only one expression completes the sentence You are ____ common sense in a way that is both grammatically correct and idiomatic in formal English. Understanding such fixed combinations is important for competitive exams and for accurate written and spoken communication.

Given Data / Assumptions:

The sentence to complete is: You are ____ common sense.

All options are short phrases that must fit directly after the verb are.

The intended meaning is that the person does not have common sense.

We assume standard modern British or Indian English usage for exams.

We also assume that only one option is fully correct and natural.

Concept / Approach:

Two key ideas are tested here. First, some adjectives and nouns always take specific prepositions or patterns, called collocations. Second, certain expressions are simply not used in correct English, even if they appear to follow a pattern. The adjectives lacking and devoid both express absence, but they combine with different prepositions. The adjective devoid is followed by of, while lacking is usually followed by in or is used without any preposition in some structures. Therefore, we must examine each option and compare it with standard collocations.

Step-by-Step Solution:
Step 1: Read the base sentence: You are ____ common sense. Step 2: Test option a: You are lacking of common sense. This is incorrect, because lacking of is not a standard combination. Step 3: Test option b: You are devoid in common sense. This is incorrect, because devoid takes of, not in. Step 4: Test option c: You are devoid of common sense. This is correct and idiomatic and directly means that you do not have common sense. Step 5: Test option d: You are dull of common sense. This sounds unnatural and is not a standard expression. Step 6: Test option e: You are dull on common sense. This is also ungrammatical and not used in standard English. Step 7: Conclude that only devoid of produces a fully correct and natural sentence.

Verification / Alternative check:

We can cross check by replacing the blank with other known collocations. A very common phrase is He is devoid of emotion or The story is devoid of logic. In each case, the structure is be + devoid of + noun. Replacing common sense into this pattern gives You are devoid of common sense, which fits perfectly. In contrast, native usage never says lacking of; people say lacking in experience or simply lacking experience. This reinforces that devoid of is the single correct choice.

Why Other Options Are Wrong:

Option a (lacking of) is wrong because lacking does not take of in this structure. The phrase is ungrammatical.

Option b (devoid in) is wrong because devoid must be followed by of, not in.

Option d (dull of) is not a recognised collocation and does not convey the intended meaning of lacking common sense.

Option e (dull on) is grammatically incorrect and sounds very unnatural.

Common Pitfalls:

Candidates often rely on direct translation from their first language and try to force a general rule like adjective plus of. However, English contains many fixed expressions that must be learned as they are used by proficient speakers. Another common mistake is assuming that lacking of is parallel to a lack of and therefore acceptable. In reality, a lack of is correct as a noun phrase, but lacking of is not correct as a verb or adjective phrase. Learning the difference between devoid of, full of, short of, and lacking in will reduce such errors.

Final Answer:

The correct expression that completes the sentence in a grammatically accurate and natural way is devoid of.