All divine books invited people to worship one God, and contained belief in prophethood, the Day of Judgement, accountability before God.
Along with these teachings the revealed books contained a code of conduct, a code of morality and justice, but the books besides the Qur’an were not comprehensive enough to contain a complete code of life for all times.
None the revealed books besides the Qur’an are in their original form today
The Qur’an is the most comprehensive book sent by God.
God says, ‘This day I have perfected your religion for you and completed my favours upon you and chosen for you Islam as your religion’. (Al Maidah 5:3).
Answers could also talk about the finality of the Prophet Muhammad (pbuh) and the Qur’an being the last universal and most perfect book of guidance sent by God to humankind for all ages.