The correct option is Vishnudharmottara Purana.
Explanation
The Chitrasutra is widely regarded as the oldest and most authoritative treatise on the canons of Indian painting. It provides the theoretical foundation for the aesthetic and technical standards observed in classical Indian art, particularly the mural traditions of the Gupta and Vakataka periods (e.g., Ajanta).
- Vishnudharmottara Purana: The Chitrasutra constitutes Part III (Khanda III), Chapters 35 to 43 of the Vishnudharmottara Purana. It is presented as a dialogue between Sage Markandeya and King Vajra. The text elaborates on the rules of image-making, encompassing dimensions, proportions, perspective (kshayavriddhi), the preparation of surfaces, and the use of colors.
- Brihat Samhita: Authored by Varahamihira (6th century CE), this is an encyclopedic work focusing on astrology, planetary movements, architecture, and natural phenomena. It does not contain the Chitrasutra.
- Silparatna: A 16th-century Sanskrit text on architecture and iconography written by Srikumara, associated with the Kerala school. It is a later medieval text.
- Manasollasa: Authored by the Western Chalukya King Someshvara III (12th century CE), this encyclopedic text covers various subjects including governance, ethics, and entertainment. While it includes a section on painting (Alekhya Karma), it is distinct from the Chitrasutra.
Key Takeaway: The Chitrasutra, the seminal text defining the grammar of Indian painting, is a section within the Vishnudharmottara Purana.