Concept:Knowing the timeline of the Prophet’s life and the deaths of his close family members.Explanation:Khadija died in the tenth year after the Prophethood began.That year corresponds to 619 C.E., specifically in the month of Ramadan.The Prophet called this period the “Year of Sorrow” because his uncle and protector Abu Talib also died around the same time.Thus, among the given options, 619 C.E. is correct.Answer:C. 619 C.E.