Final answer:
The Book of the Dead, with its protective spells for the afterlife, as well as the elaborate tombs and mummification rituals, are compelling evidence that the ancient Egyptians prepared for the afterlife.
Step-by-step explanation:
The best-supporting evidence for the central idea that the ancient Egyptians prepared for the afterlife is Option A) The Book of the Dead is a collection. The Book of the Dead contains protective spells designed to assist the soul in the afterlife, demonstrating preparation for the afterlife journey.
Additionally, the construction of tombs for the pharaohs, preserving their bodies within massive pyramids, and beliefs in the spiritual elements such as the Ka and Ba, which needed the physical body for sustenance after death, all underline the Egyptians' focus on the afterlife.
The elaborate decorations and offerings in these tombs further reflect the belief in a world to come where the virtuous could attain eternal life, and the unworthy would face judgement by the god Osiris and potential destruction of their souls.