Which of the Following Equations Defines the Tube Dilution in a Serial

Which of the following equations defines the tube dilution in a serial dilution?

A) $\frac{V_{\text {sam ple }}}{V_{\text {sample }}+V_{\text {diluent }}}$
B) $\frac{\text { Number of tubes }}{\mathrm{V}_{\text {sample }}+\mathrm{V}_{\text {dilent }}}$
C) $\frac{V_{\text {sample }}}{V_{\text {sample }} \times \text { Number of tubes }}$
D) $\frac{V_{\text {sample }}}{{\text {Number of tubes }} \div \text {V}{ diluent}}$