Quarks inside protons and neutrons are through to carry factional charges $\bigg[+\bigg( \large\frac{2}{3}\bigg):\bigg( \large\frac{-1}{3}e\bigg)\bigg]$ why do they not show up in Millikan's oil-drop experiment ?

Question

$\begin{array}{1 1}\text{When quakes are pulled apart , they become stronger } \\ \text {They get apart easily when they are parallel} \\ \text{They always remains together } \\ \text{They are always integral multiplies of charge } \end{array} $