The diffusion coefficient of a protein in a buffered solution at $20\backslash$deg C was measured using a

concentration gradient between two reservoirs with concentrations of $100\backslash$mu M and $1\backslash$mu M respectively.

The two reservoirs were separated by a $1$ mm thick, porous glass disk with a $3\mathrm{.}5$ cm$2$ effective area.

About $0\mathrm{.}1\backslash$mu mols of the protein were detected to be crossing the disk per hour. What is the diffusion

coefficient D of the protein?

$($A$)9\mathrm{.}4$ x $10-6$ cm$2$ s$-1$

$($B$)8\mathrm{.}0$ x $10-6$ cm$2$ s$-1$

$($C$)4\mathrm{.}0$ x $10-7$ cm$2$ s$-1$

$($D$)4\mathrm{.}2$ x $10-6$ cm$2$ s$-1$

$($E$)6\mathrm{.}5$ x $10-6$ cm$2$ s$-$