If a person is performing Wudu, but blood continues to flow from a deep wound on their arm, why is the Wudu invalid?

Ablution (الوضوء): Conditions of Obligation and Validity

• Because blood is a solid barrier.
• Because Wudu requires the cessation of any active, invalidating emissions (inqitā' mā yunāfī) during the act.
• Because blood has no color.
• Because the water used was cold.