Concept: The essential acts within Muslim prayer (Salat) are called pillars; Ruku is one of these pillars.
Explanation:• Tarawih is a special voluntary prayer performed at night, not a core part of every Salat.
• Ruku is the bowing position, a mandatory pillar within every unit of Salat.
• Taslim is the salutation that ends the prayer, but it is not the most important part.
• Wudu is the purification done before prayer, not an act performed during Salat.
So, among the options, Ruku is the most important part of performing Salat.
Answer: B. Ruku