Concept:"Simple" language is plain and easy to understand. The opposite (antonym) is "complex": complicated and difficult to understand.
Solution:The question asks for the word opposite in meaning to "simple".
"The story was written in complex language" gives the exact opposite idea.
A. "foreign" means from another country; a foreign language can still be simple.
B. "strange" means unusual, not difficult.
C. "local" means of a particular place; it says nothing about difficulty.
Key point: An antonym must be opposite on the same scale (easy vs difficult), not just different.
Answer:Option D (complex)