Anup Rag Vilas' is a book written by which of the following musicians?

The correct option is Pandit Kumar Gandharva.

Step-by-step explanation:

1. Identify the book and author: "Anup Rag Vilas" (often transliterated as Anup Raga Vilas or Anoop Raag Vilas) is a well-known treatise and collection of musical compositions (bandishes) written by the legendary Hindustani classical vocalist, Pandit Kumar Gandharva.
He was famous for his path-breaking contributions to classical music, including creating new ragas and blending folk music with classical structures.

2. Analyze the options:
- Pandit Jasraj: A doyen of the Mewati Gharana, known for his classical singing and devotional music, but not the author of this work.
- Pandit Birju Maharaj: A legendary Kathak dancer, choreographer, and musician of the Lucknow Kalka-Bindadin Gharana.
- Pandit Kumar Gandharva: The renowned vocalist and composer who authored "Anup Rag Vilas," compile-recording his original compositions and perspectives on ragas.
- Pandit Dinkar Kaikini: A renowned vocalist of the Agra Gharana and composer, but not the author of this specific book.

Therefore, the book "Anup Rag Vilas" was written by Pandit Kumar Gandharva.