To answer this question, you need to know which country uses the currency known as the yen.
Option A) Japan - This option is correct because the yen is the currency of Japan.
Option B) China - This option is incorrect because the currency of China is the yuan (also known as the renminbi).
Option C) Nepal - This option is incorrect because the currency of Nepal is the Nepalese rupee.
Option D) Bhutan - This option is incorrect because the currency of Bhutan is the Bhutanese ngultrum.
The correct answer is Option A) Japan. The yen is the currency of Japan.