Question

where is there a low concentration of due? no concerteraion gradient at the bottom of cup at the top of cup in the color

Explanation:

When considering the distribution of a substance (assuming "due" is a typo for a substance like "dye"), in a cup without external forces (like stirring), substances tend to diffuse. Dye would initially be more concentrated where it is placed (e.g., if poured in, maybe at the bottom). Over time, it diffuses. But if we assume a simple scenario of initial placement and no stirring, at the top of the cup (if dye was poured in and starts to diffuse up), the concentration would be lower compared to the area where it was initially placed (like the bottom). "No concentration gradient" would mean uniform distribution (not low in a specific place). "In the color" is a non - sensical option in this context.

Answer:

at the top of cup