Firstly you should
think over the meaning of the words
and then use them
No error
Answer is Right!
Answer is Wrong!
The correct answer is: D. No error
The sentence is grammatically correct. The word “firstly” is an adverb that introduces a list of items, and the word “then” is a conjunction that joins two clauses. The sentence is clear and easy to understand.
The other options are incorrect because they contain grammatical errors. Option A is incorrect because the word “should” is not followed by an infinitive. Option B is incorrect because the word “over” is not used correctly. Option C is incorrect because the word “and” is not used correctly.