An electric hoover price is decreased from $$160$ to $$180($a change of $-12\mathrm{.}5$ percent$)$ and this decrease causes an increase in sales from $360$ units to $450$ units $($a change of $+25$ percent$),$ then the price elasticity would be:

a$.2$

b$.-1\mathrm{.}5$

c$.1\mathrm{.}5$

d$.-2$