Four different spellings of the same word are given. Choose the correctly spelt form of the word that means "an observable fact or event" in English, commonly used in science and general studies.

Introduction / Context:
Spelling questions test your familiarity with common academic words that often appear in textbooks, articles, and exam passages. The word here is pronounced in a way that makes it easy to misspell. Mastering its correct spelling is important for written communication and for recognising it quickly when reading.

Given Data / Assumptions:
- The word refers to an observable fact, event, or occurrence, especially in a scientific context.
- The correct spelling is a singular noun, not plural.
- The options present similar looking sequences of letters with slight changes.

Concept / Approach:
The correct spelling of the singular form is "Phenomenon". The plural is "Phenomena". Many learners confuse these forms or insert extra letters. By remembering the pattern "pheno menon" for the singular and "pheno mena" for the plural, you can keep the spellings clear in your mind.

Step-by-Step Solution:
Step 1: Recall the correct singular spelling from reading textbooks or articles: "Phenomenon". Step 2: Compare each option with this spelling. Step 3: Option B exactly matches "Phenomenon". Step 4: Option A, "Phenamenon", incorrectly uses "amen" instead of "omen". Step 5: Option C, "Phenominon", uses "min" instead of "men". Step 6: Option D, "Phenomenan", wrongly ends with "an" rather than "on". Step 7: Option E, "Phenomemon", swaps letters in the middle and is incorrect.

Verification / Alternative check:
Checking a dictionary or any standard science textbook will show "Phenomenon" as the singular form and "Phenomena" as the plural. You may also note its usage in sentences such as "Rainbows are a natural phenomenon" or "This social phenomenon is studied by sociologists". These references confirm the spelling in Option B.

Why Other Options Are Wrong:
The other options alter the vowel and consonant sequence in the middle or at the end. English spelling is often irregular, but for this academic word the spelling is fixed. Any variation such as "amenon", "minon", or "menan" is simply wrong and will not appear in quality writing or dictionaries.

Common Pitfalls:
Many learners confuse the singular and plural forms, writing "Phenomena" when they mean one event or "Phenomenon" when they refer to several. Another frequent error is inserting extra letters or vowels to match the pronunciation, which can mislead the eye. Repeated exposure to the correct forms in reading and practice can help strengthen your memory of the spelling.

Final Answer:
The correctly spelt word is Phenomenon.