Four words are given, out of which only one word is spelt correctly. Choose the correctly spelt form of the word meaning "the most perfect example or pure essence of something".

Introduction / Context:
This spelling question focuses on a slightly advanced English word that often appears in literature and formal writing. The word refers to the pure, most perfect embodiment of a quality or type. Being able to spell such abstract nouns correctly is important in descriptive and analytical writing, as well as in competitive exams.

Given Data / Assumptions:

The word under test is pronounced /ˌkwɪnˈtɛsəns/ and means "the most perfect example or essence of something".
The correct spelling is derived from the Latin roots for "fifth essence".
Options show common misspellings that change letters near the end of the word.

Concept / Approach:
The standard spelling is "quintessence": q-u-i-n-t-e-s-s-e-n-c-e. Notice the double "s" in the middle and the ending "-ence". Many English abstract nouns end with "-ence" or "-ance", and it is easy to confuse the two suffixes. However, in this specific word, dictionaries confirm the "-essence" pattern, giving quintessence. Any version that replaces "-ence" with "-ance" or rearranges letters in the core is incorrect.

Step-by-Step Solution:
Step 1: Recall the standard form: quintessence. Step 2: Examine option B "Quintessence". It matches the expected sequence: quin + t + essence. Step 3: Option A "Quintessance" uses "-ance" at the end, which is a common but wrong variation. Step 4: Option C "Quaintessence" introduces "quaint" instead of "quin", completely altering the root. Step 5: Option D "Quintassence" replaces "ess" with "ass", breaking the pattern and changing pronunciation. Step 6: Option E "Quintescense" incorrectly adds "scen" instead of "sence", another typical error in words ending with "-ence".

Verification / Alternative check:
Use the word in a sentence: "She is the quintessence of kindness." This is a standard phrase that you may see in books or articles. If we substituted "quintessance" or "quintassence", the words would look wrong and you would not find them in reliable dictionaries. Recognising the root "essence" within the spelling helps; quintessence literally resembles "quin + essence", further confirming that the ending must be "-essence", not any of the variants shown.

Why Other Options Are Wrong:
Option A Quintessance uses "-ance" instead of "-ence" and does not match the standard spelling.
Option C Quaintessence begins with "quaint", a different word meaning old-fashioned or charming, making it incorrect as a spelling for "quintessence".
Option D Quintassence alters the core "essence" to "assence", which is not recognised in English.
Option E Quintescense wrongly inserts "scen" and is a typical spelling mistake seen with words like "presence" and "essence".

Common Pitfalls:
Learners often confuse the endings "-ance" and "-ence", as both are common in abstract nouns. One helpful strategy is to memorise a few key words like presence, essence, and quintessence with "-ence" to set a pattern in your mind. Another tip is to notice internal patterns like "essence" inside the word, which strongly suggests the correct form. Whenever in doubt, think of similar known words and compare their endings.

Final Answer:
The correctly spelt word is "Quintessence".