The colour of a colloidal solution is due to

The conditions given below are in the context of observing Tyndall effect in colloidal solutions:
$A$. The diameter of the colloidal particles is comparable to the wavelength of light used.
$B$. The diameter of the colloidal particles is much smaller than the wavelength of light used.
$C$. The diameter of the colloidal particles is much larger than the wavelength of light used.
$D$. The refractive indices of the dispersed phase and the dispersion medium are comparable.
$E$. The dispersed phase has a very different refractive index from the dispersion medium.
Choose the most appropriate conditions from the options given below:

Which experimental method and instrument are used to measure the colloidal properties of a polymer solution?

In the Tyndall effect,colloidal particles .....

What is the cause of the Tyndall effect in a colloidal solution?

When an excess of $AgNO_3$ solution is added to a $KI$ solution,a sol is formed. The colloidal particles will carry which type of charge?