In this spelling question, four different spellings of the same word are given. Select the correctly spelt form of the word meaning "showing an unhealthy obsession or excessive concern".

Introduction / Context:
This question tests your knowledge of correct English spelling. Spelling questions are common in many competitive exams because they check not only memory but also your familiarity with standard written English. The word in focus here is "obsessive", which is used to describe someone who is excessively preoccupied with a particular idea, activity, or person.

Given Data / Assumptions:

• You are given four main variants: "obsesive", "obsessiv", "obsessive", and "obsesiv", along with one extra incorrect option.
• Only one spelling is standard and accepted in formal English.
• The base word is "obsess", and the adjective form is built from it.

Concept / Approach:
To identify the correct spelling, it helps to know the base verb "to obsess" and the related noun "obsession". The adjective is formed by adding "ive" to the base "obsess". Thus, the correct spelling is "obsessive", with double "s" in the middle and the final "ive" ending. Options that drop a letter, change the ending, or distort the base form are incorrect. Learning word families like obsess, obsession, obsessive can help you reliably choose correct spellings in exams.

Step-by-Step Solution:
Step 1: Identify the root word, which is "obsess". Step 2: Recall the noun form "obsession" and adjective "obsessive". Both keep the double "s" after the "b". Step 3: Examine option C "obsessive". It keeps the full base "obsess" and adds the adjective suffix "ive". Step 4: Check option A "obsesive". It has only one "s" after "b", so it is wrongly spelt. Step 5: Check option B "obsessiv". It lacks the final "e" required by the "ive" ending. Step 6: Check option D "obsesiv". It omits both an "s" and the final "e", so it is completely wrong. Step 7: Option E "obessive" misplaces the letters and does not match the base word "obsess".

Verification / Alternative check:
You can verify from memory by recalling phrases such as "obsessive behaviour", "obsessive thoughts", or "obsessive fan". In all these real life usages, the printed form is "obsessive". Seeing the word used in reliable sources like textbooks, newspapers, and dictionaries reinforces the correct pattern. None of the other given spellings look familiar in standard written English.

Why Other Options Are Wrong:
Option A misses one "s", which breaks the clear link to the base word "obsess". Option B truncates the adjective ending, stopping at "v". Option D changes both the number of consonants and the ending, and option E rearranges letters, producing a nonstandard form. None of these appear in dictionaries as correct spellings of the adjective.

Common Pitfalls:
A frequent problem is that learners rely on pronunciation instead of visual memory when choosing spellings. Since the double "s" is not strongly heard, many guess a single "s". To avoid this, practise spelling by writing and revising entire word families, and pay special attention to double consonants in English words like "necessary", "occasion", and "obsessive". Over time, correct spellings will start to look visually natural, and incorrect ones will stand out as strange.

Final Answer:
The correctly spelt word is obsessive.