In this spelling question, four options are given. Select the correctly spelt English word.

Introduction / Context:
Spelling questions test how familiar you are with standard English vocabulary. Here you are asked to identify the correctly spelt word from a list of near lookalikes. The word "thespian" is a common English term used to refer to an actor or someone related to the theatre and dramatic arts. Recognising such words is important for reading comprehension and formal writing in competitive exams and professional communication.

Given Data / Assumptions:

• Four main options are given: "oxidieser", "thespian", "aproval", and "secreetes", plus an additional distractor.
• Only one word is spelled correctly according to standard English dictionaries.
• The question does not ask for meaning directly, but knowing the meanings helps identify genuine words.

Concept / Approach:
A reliable method for spelling questions is to look for patterns you have seen in reliable sources such as books, newspapers, and academic materials. "Thespian" is a recognised adjective and noun that means "relating to drama and the theatre" or "an actor". The other options look like misspellings of "oxidiser" (or "oxidizer"), "approval", and "secretes". Even if you do not know the exact correct spellings of the incorrect options, you can often eliminate them by noticing that extra letters, wrong vowels, or doubled consonants have been inserted in the wrong places.

Step-by-Step Solution:
Step 1: Look at "thespian". If you have encountered theatre related vocabulary, you may recall the phrase "thespian society" or "thespian awards". The spelling looks complete and familiar. Step 2: Examine "oxidieser". The more standard forms are "oxidiser" (British English) or "oxidizer" (American English). The sequence "dies" in the middle shows the word is misspelt. Step 3: Look at "aproval". The correct spelling is "approval" with double "p", so this option is also incorrect. Step 4: Check "secreetes". This seems to be a wrong attempt at "secretes", which is spelled with only one "e" in the second syllable, not "ee". Step 5: The extra distractor "thespien" changes the final vowel and does not match the known correct word "thespian". Step 6: Since all other options are clearly nonstandard, "thespian" must be the correctly spelt word.

Verification / Alternative check:
You can verify by thinking of simple example sentences: "He is a talented thespian who has performed in many plays" or "The school thespian club is organising a drama festival." In each of these, the spelling "thespian" is used. If you had to write this word in an essay about theatre, this is the form you would choose, which confirms its correctness.

Why Other Options Are Wrong:
"Oxidieser" contains an incorrect internal sequence of letters, "aproval" misses a crucial "p", "secreetes" adds an extra "e" that does not belong, and "thespien" alters the vowel pattern. None of these appear as correct spellings in standard dictionaries, which is why they are distractors in this question.

Common Pitfalls:
Students often rely on how a word sounds and may be misled by similar looking wrong options. English spellings frequently contain silent letters and unexpected double consonants, so listening alone is not enough. Developing a habit of reading widely and paying attention to spellings helps build visual memory of words like "thespian". Over time, incorrect forms will automatically look strange to you, making such questions much easier.

Final Answer:
The correctly spelt word is thespian.