[tex] \frac{(6{x}^{5}z)^{3}}{4{x}^{4}z^{2}}=\frac{{6}^{3}{x}^{15}{z}^{3}}{4{x}^{4}{z}^{2}}=\\\frac{{6}^{3}{x}^{15 - 4}{z}^{3 - 2}}{{2}^{2}}=\frac{{3}^{3}\times{2}^{3}{x}^{11}z}{{2}^{2}}=\\{3}^{3}\times{2}^{3 - 2}{x}^{11}z=27\times2{x}^{11}z=\\54{x}^{11}z[/tex]
The answer is b
