According to the 10% of 10% rule, how much blood can be safely collected from a 100 g gerbil?

• A. 1 mL
• B. 10 mL
• C. 0.1 mL
• D. 5 mL

Answer: (A)

The main idea is estimating safe blood volume from body weight using the 10% of 10% rule. Total blood volume in small mammals is about 10% of their body weight, so a 100 g animal has roughly 10 mL of blood. Taking 10% of that amount to avoid destabilizing the animal gives about 1 mL. So, for a 100 g gerbil, approximately 1 mL is the maximum safe amount to collect in a single draw. The other options exceed the safe limit (or are far below it), making them not suitable for a safe single collection.