Umm al-Tafsir is:

Tafsir Tabari, also known as Jami' al-Bayan 'an Ta'wil Ayi al-Qur'an, is widely regarded as Umm al-Tafsir (the Mother of Tafsir). Authored by Imam Abu Ja'far Muhammad ibn Jarir al-Tabari, it is celebrated for its comprehensive nature, reliance on early sources, and profound influence on subsequent Quranic exegesis.

• Tafsir Tabari is the correct answer due to its foundational status and comprehensive methodology.
• Tafsir Qurtubi, Tafsir Baidawi, and Tafsir Jalalain are all important and widely studied works of tafsir, but they were composed later and often built upon the groundwork laid by Tafsir al-Tabari.