Concept:Abstruse means something that is hard to understand or obscure. Its synonym is a word with a similar meaning of complexity.
Explanation:The word "Abstruse" means difficult to understand or obscure (जटिल, कठिन).
For example: Quantum physics is an abstruse subject for most people.
The word "Difficult" means requiring effort or skill to accomplish or understand (कठिन).
Both words share the idea of being hard to grasp.
Hence, the correct synonym is "Difficult".
The other options are opposite in meaning: Obvious, Simple, and Clear all mean easy to understand.
Answer:A. Difficult