Which expression is equivalent to m 4 q 4 z - 1 m q 5 z

Choice B is correct. Applying the commutative property of multipliion, the expression $\left(m^4{q}^4{z}^{-1}\right)\left(m{q}^5{z}^3\right)$ can be rewritten as $\left(m^{4}m\right)\left(q^4{q}^5\right)\left(z^{-1}{z}^3\right)$. For positive values of $x$, $\left(x^a\right)\left(x^b\right)=x^{a+b}$. Therefore, the expression $\left(m^{4}m\right)\left(q^4{q}^5\right)\left(z^{-1}{z}^3\right)$ can be rewritten as $\left(m^{4+1}\right)\left(q^{4+5}\right)\left(z^{-1+3}\right)$, or $m^5{q}^9{z}^2$.

Choice A is incorrect and may result from multiplying, not adding, the exponents.

Choice C is incorrect and may result from conceptual or calculation errors. 

Choice D is incorrect and may result from conceptual or calculation errors.