In this spelling question, four different spellings are given. Select the correctly spelt word that refers to an ordinary non military person or someone who is not in the armed forces.

Introduction / Context:
This question assesses your spelling skills in English. The task is to identify the correctly spelt word among several incorrect options. The correct answer, "civilian", is a commonly used term that refers to any person who is not a member of the armed forces or police. Spelling accuracy is essential in exams, formal writing, and professional communication.

Given Data / Assumptions:

• You are given the spellings "deriesion", "apalled", "civilian", "sacluded", and "civillian".
• Only one of these is correctly spelt in standard English.
• The question is about general vocabulary, not about specialised technical terms.

Concept / Approach:
The correct spelling "civilian" is built from the base "civil" plus the suffix "ian". The word is widely used in news reports, law, and everyday speech to distinguish non military people from soldiers or officers. The other options are misspellings of different words: "derision", "appalled", "secluded", or doubled wrong forms. Recognising familiar words and their typical visual patterns is the key to solving such questions quickly.

Step-by-Step Solution:
Step 1: Look at option C "civilian". This word is well known and clearly spelt with one "l" and one "i" after "civ". Step 2: Check the meaning. "Civilian" refers to a person who is not serving in the armed forces or police, which is a common English word. Step 3: Examine option A "deriesion". The standard word is "derision", so this spelling is incorrect. Step 4: Examine option B "apalled". The correct spelling is "appalled" with double "p" and double "l". Step 5: Examine option D "sacluded". The correct form is "secluded", which is spelt differently. Step 6: Examine option E "civillian". This incorrectly doubles the letter "l". The standard spelling has only one "l". Step 7: Therefore, the only correctly spelt word among the options is "civilian".

Verification / Alternative check:
You can verify the correctness of "civilian" by recalling phrases like "civilian casualties", "civilian life", and "civilian clothes", all of which appear frequently in newspapers and news broadcasts. None of the other forms would be recognised in such contexts. Visual familiarity with the correct spelling helps you confidently reject the wrong variants.

Why Other Options Are Wrong:
"Deriesion" misplaces vowels and does not match the standard word "derision". "Apalled" misses one "p" and one "l" compared to "appalled". "Sacluded" changes both vowels and consonants from the correct "secluded". "Civillian" adds an unnecessary extra "l". None of these forms are accepted in standard English dictionaries or formal writing.

Common Pitfalls:
Many learners are confused by double consonants and vowel positions in English words. They may add or remove letters randomly. To avoid such mistakes, it is important to read widely, pay attention to spellings in reliable sources, and practise writing commonly confused words. Over time, your visual memory of correct forms like "civilian" will become strong enough that incorrect variants will look obviously wrong.

Final Answer:
The correctly spelt word in the list is civilian.