Answer
D.
Work Step by Step
$\frac{x-4}{\frac{x+3}{x-1}}$
In essence, a fraction is a way to write a division. In a fraction, the numerator is the dividend and the denominator is the divisor. Thus, we can rewrite this expression as: $(x-4)\div\frac{x+3}{x-1}$.
$(x-4)\div\frac{x+3}{x-1}=(x-4)\times\frac{x-1}{x+3}=\frac{(x-4)(x-1)}{x+3}=\frac{x^2-x-4x+4}{x+3}=\frac{x^2-5x+4}{x+3}$ (choice D).
