What is the book that contains the most authoritative opinion (al-qawl al-rājiḥ) in the Madhhab of Imam Ahmad, and how can the most authoritative opinion be distinguished if this book is not available?

The Maliki school of thought, like other schools, contains various narrations, interpretations, and derivations. Ascertaining the preponderant opinion among them requires extensive study. The best book to aid in this is "Al-Insaf fi Ma'rifat al-Rajih min al-Khilaf" by Al-Mardawi. If that is difficult, one can rely on concise texts that focused on the preponderant narration, such as "Zad al-Mustaqni'" by Al-Hajjawi, and "Matn al-Dalil" by Al-Mar'i al-Karmi, along with paying attention to the books of Al-Muwaffaq Ibn Qudamah.