What is the concentration unit used in this protocol?

• A. F/mm^2
• B. F/L
• C. F/cc
• D. F/μL

Answer: (C)

Concentration is defined as the amount of substance per unit volume. In this protocol, the volume basis is cubic centimeters, so expressing the measure as F per cc ties the amount directly to the three-dimensional space of the sample. Since 1 cubic centimeter equals 1 milliliter, this choice also aligns with common lab practice when working with solutions or tissue volumes described in small, real-world volumes.

Using a per-volume unit that references area (per mm^2) or a vastly larger volume (per liter) would misrepresent how the substance distributes through the actual sample. A per microliter unit is possible, but it can complicate comparisons across samples of different sizes; per cubic centimeter keeps calculations intuitive and consistent with typical tissue or small-volume measurements.

So, F/cc is the best fit because it expresses the amount relative to a volume that matches how the protocol describes and handles the sample.