Evaluate the integral: ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{19}{x^2\sqrt[\phantom{2}]{x^{2}49}}dx$

$($A$)$ Which tris substitution is correct for this integral?

$x=7tan()$

$x=49tan()$

$x=49sin()$

$x=49sec()$

$x=19sec()$

$x=7sin()$

${}^4$

$($b$)$ Which integral do you obtain after substituting for $x$ and simplifying? Note: to enter $,$ type the word theta.

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$($C$)$ What is the value of the above integral in terms of $?$

$x*c$

$($D$)$ What is the value of the original integral in terms of $x?$

$c$