Concept:The nickname “as-Sadiq” means “the truthful one.” It reflects a personal quality that Abu-Bakr was known for.Explanation:Abu-Bakr received the title “as-Sadiq” because he always spoke the truth.He was given this name even before Islam, due to his honesty and upright character.The title became especially famous when he immediately confirmed the Prophet’s night journey to Jerusalem, without doubt.This act of firm belief in the truth strengthened his reputation as a truthful companion.Answer:D. truthfulness