Which expression simplifies...

Answer:
see below
Step-by-step explanation:
If suffices to look at the last term. It must simplify to 4/(3w²), so the exponents of z must match in numerator and denominator, and the ratio of constants must reduce to 4/3.
The exponents of z have the right values in choices B and D, but the ratio of constants only matches in choice D. Looking at the rest of choice D, we see that we can factor 6w²z² from both numerator and denominator, then factor 2 from the remaining numerator to make it match the desired form.
[tex]\dfrac{(12w^2z^4-24w^2z^2)}{18w^4z^2}=\dfrac{6w^2z^2}{6w^2z^2}\cdot\dfrac{2z^2-4}{3w^2}=\dfrac{2(z^2-2)}{3w^2}[/tex]