A. praying with his family every morning
In Shinto, rituals and daily practices often involve prayer and offering to kami (spirits or deities) and ancestors, making option A the most likely part of Keiji's religious practice. Honoring ancestors is also significant in Shinto, but the act of praying daily aligns more directly with typical Shinto practices. Options B and C do not align with Shinto beliefs, and option D, while related to honoring ancestors, is more indirect compared to the daily practice of prayer.