The given expression is
[tex](-5x^2y)(3x^4)[/tex]We will multiply at first -5 by 3
[tex]-5\times3=-15[/tex]Then we will multiply x^2 by x^4 by adding their powers
[tex]x^2\times x^4=x^{2+4}=x^6^{}[/tex]And multiply y by 1 as there is no y in the second bracket, then
[tex](-5x^2y)(3x^4)=-15x^6y[/tex]The answer is C