The data in the following table were obtained during the determination of potassium by flame emission spectroscopy using Lithium as an internal standard. The potassium concentration in ppm is:

A$.10\mathrm{.}68ppm$

B$.5\mathrm{.}79ppm$

C$.5\mathrm{.}25ppm$

D$.6\mathrm{.}18ppm$

$\backslash$table$[[\backslash$table$[[$K concentration,$],[$ppm$]],K$ K intensity,Li intensity K$/$Li intensity$],[10\mathrm{.}0,10\mathrm{.}0,1\mathrm{.}0],[2\mathrm{.}00,15\mathrm{.}3,7\mathrm{.}5,2\mathrm{.}0],[5\mathrm{.}00,34\mathrm{.}7,6\mathrm{.}8,5\mathrm{.}1],[7\mathrm{.}50,65\mathrm{.}2,8\mathrm{.}5,7\mathrm{.}7],[10\mathrm{.}00,95\mathrm{.}8,10\mathrm{.}0,9\mathrm{.}6],[20\mathrm{.}00,110\mathrm{.}2,5\mathrm{.}8,19\mathrm{.}0],[$Sample$?,47\mathrm{.}3,9\mathrm{.}1,5\mathrm{.}2]$

In the equation to find the standard deviation of concentration $($Sc$),$ the parameter $M$ corresponds to the number of:

A$.$ Replicas

B$.$ Samples

C$.$ Standards

D$.$ Solutions