When the price of candy bars decreased from $$0\mathrm{.}55$ to $$0\mathrm{.}45,$ the quantity demanded changed from $19,000$ per day to $21,000$ per day in this price range, the prik $($based on the midpoint formula$)$ is

Multiple Choice

$-1.$

$-2.$

$-0\mathrm{.}2$

$-0\mathrm{.}5.$