Voldemort created 7 Horcruxes in total: the diary, Marvolo Gaunt's ring, Slytherin's locket, Hufflepuff's cup, Ravenclaw's diadem, Nagini the snake, and Harry Potter (the unintended 7th Horcrux). This number is significant because Voldemort sought to split his soul into 7 pieces, which he believed to be the most magically powerful number. The other options are incorrect as they don't match the canonical count from the series.