Final answer:
The Sunna is a collection of teachings consisting of the Prophet Muhammad's sayings, actions, and approvals, guiding Muslims on how to live. It is distinct from the Hijab, which is a veil; the Imam, a religious leader; and the Kaaba, a holy site in Islam.
Step-by-step explanation:
The answer is: a) Sunna. In Islam, the Sunna refers to a compilation of traditions which include the sayings, actions, and approvals of the Prophet Muhammad. These traditions complement the teachings of the Quran and help Muslims understand how to live their lives according to Islamic principles.
The Hijab refers to a veil worn by some Muslim women, the Imam is a Muslim leader, often leading prayers in a mosque, and the Kaaba is the sacred structure within the Masjid al-Haram in Mecca which Muslims face during their five daily prayers and is the focal point of the annual pilgrimage, or hajj. It is worth noting that in Shia Islam, a student is less likely to be taught that the "Four Rightly Guided" caliphs should be respected as the first imams and more likely to learn that leadership should descend from the Prophet Muhammad.