The legend of Prahlad and his father Hiranyakashyap is a story from Hindu mythology. Hiranyakashyap was a power-hungry king who wanted everyone to worship him instead of the gods. However, his son Prahlad was a devout follower of Lord Vishnu. Despite Hiranyakashyap`s attempts to kill Prahlad, the young boy`s devotion to Vishnu remained unwavering. Eventually, Vishnu appeared in the form of Narasimha, a half-man, half-lion creature, and killed Hiranyakashyap to protect Prahlad.

To understand which purana contains the legend, let`s review the options:

1. Bhagwat Purana: This purana focuses on the life and teachings of Lord Krishna. While it contains various stories from Hindu mythology, the legend of Prahlad and Hiranyakashyap is not specifically mentioned here.

2. Vishnu Purana: This purana is dedicated to Lord Vishnu and covers various aspects of his life, including his incarnations. As the legend of Prahlad and Hiranyakashyap revolves around Lord Vishnu, it is most likely to be found in this purana.

3. Vamana Purana: This pur