Step 1: Understanding the Concept:
The Upapuranas are classified based on the primary deity they glorify. While the name 'Nandikeshvara' (the lord of Nandi) typically suggests a connection to Shiva, several Puranas have titles that do not immediately reveal their sectarian focus. The Brihannandikeshvara Purana is a specific text that requires careful identification.
Step 2: Detailed Explanation:
The Brihannandikeshvara Purana is classified as a Shakta-puranam. Although Nandikeshvara is the narrator (Shiva's chief attendant), the primary subject matter of this specific Upapurana is the worship of the Divine Mother (Shakti).
It contains detailed descriptions of Durgapuja, the various forms of the Goddess (like Mahishamardini), and the rituals associated with the Shakta cult. It is particularly influential in the Eastern parts of India (Bengal and Assam), where it is cited as a major authority for the performance of the Durga Puja festivals. This makes it a central text for the Shakta tradition.
Distinguishing from others:
- Shaiva-puranam (Option C): These would focus on Shiva's forms and Linga worship (e.g., Shiva-rahasya).
- Saura-puranam (Option A): These focus on the Sun (e.g., Samba Purana).
- Vaishnava-puranam (Option D): These focus on Vishnu/Krishna (e.g., Vishnudharmottara).
Because the Brihannandikeshvara is the foundational text for many Goddess-centric rituals, it belongs to the Shakta category. This is a classic example in Indology where the 'speaker' (Nandi) is Saiva, but the 'content' (Devi) is Shakta.
Step 4: Final Answer:
It is a Shakta-puranam.