If $x 
eq y$, then $\frac{x-y}{y-x}=-1$. We use this fact to simplify the original expression: $$ \frac{2a-6}{5-c} \cdot \frac{b-4}{3-a} \cdot \frac{2c-10}{4-b} = -2\times 2= 4$$. 
Assuming $a 
eq 3, b 
eq 4$, and $c 
eq 5$, what is the value in simplest form of the following expression? (Adapted From 2020 AMC 10A Problems, Question \#3)  $$ \frac{2a-6}{5-c} \cdot \frac{b-4}{3-a} \cdot \frac{2c-10}{4-b} $$ 
Options:
(1) $$2$$ 
(2) $$-4$$ 
(3) $\frac{a b c}{15}$ 
(4) $\frac{4}{a b c}-\frac{1}{15}$ 
(5) $\frac{1}{15}-\frac{1}{a b c}$ 