Select the most appropriate word for the given group of words.
A written work dealing formally and systematically with a single specialized subject.

Correct option is B

The correct one-word substitution for the given definition is "Monograph".
· Monograph (एकल विषय पर लेखन) – A detailed written study or scholarly work focused on a single specialized subject.
Example:
The scientist published a monograph on climate change.
Meanings of the other options:
· Monologue – (अकेले व्यक्ति का भाषण) A long speech by one person.
· Monogram – (संक्षिप्त चिह्न) A design of initials used as a logo.
· Monolith – (एक ही पत्थर से बनी संरचना) A large single block of stone.
Thus, "Monograph" is the correct answer.