The main theme of Surah Al-Ikhlas (Chapter 112) is the oneness of Allah (Tawhid). The surah's very name, Al-Ikhlas, means "Sincerity" or "Purity of Faith," and its four concise verses provide the most concentrated statement of Islamic monotheism in the entire Qur'an:
"Qul huwa Allahu ahad" - Say: He is Allah, the One.
"Allahu as-samad" - Allah, the Eternal Refuge (the Self-Sufficient).
"Lam yalid wa lam yulad" - He neither begets nor is born.
"Wa lam yakun lahu kufuwan ahad" - Nor is there any equivalent to Him.
The Prophet (peace be upon him) said that this surah is equivalent to one-third of the Qur'an because it encapsulates the entire concept of Allah's nature and oneness, which is the foundational belief of Islam. The surah negates any form of polytheism, partnership with Allah, or attribution of human qualities such as having children or parents to Allah.
The other options are unrelated to this surah. Inheritance rules are found primarily in Surah Al-Nisa. The punishment of the grave is discussed in hadith literature. The birth of the Prophet is not a Qur'anic theme.