What is the appropriate way to preserve blood evidence?

Using paper bags as a porous material is the appropriate way to preserve blood evidence because it allows the blood to breathe and prevents the growth of mold and bacteria. Blood is a biological material that can deteriorate if moisture is trapped. Paper bags are breathable, which helps to keep the evidence dry and reduces the risk of degradation over time. This method preserves the integrity of the evidence for forensic analysis.

In contrast, plastic containers can create a sealed environment that retains moisture, which may lead to biological growth and affect the quality of the evidence. Metal containers, while durable, can also trap moisture and subsequently compromise the evidence. Glass vials, although they provide a non-reactive surface, can be risky if sealed tightly, as they do not allow for the necessary breathability that blood evidence requires to remain uncontaminated.