Evaluate the integral: ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{-25}{x^2\sqrt[\phantom{2}]{x^2+36}}dx$

a$.$ Which trig substitution is correct for this integral?

A$.x=36sec()$

B$.x=36tan()$

C$.x=36sin()$

D$.x=6tan()$

E$.x=6sin()$

F$.x=-25sec()$

b$.$ Which integral do you obtain after substituting for $x$ and simplifying?

c$.$ What is the value of the above integral in terms of $?$

d$.$ What is the value of the original integral in terms of $x?$