In specific application, the temperature is needed to be measured. In order to do so; a thermometer that reacts for every $0\mathrm{.}50C$ change of temperature is used. Given that the used device requires $1\mathrm{.}50sec$ to settle for proper temperature reading. If the temperature changed from $21\mathrm{.}05C$ to $21\mathrm{.}00C,$ then the reading of the thermometer is:

Select one:

a$.21\mathrm{.}50C$

b$.21\mathrm{.}00C$

c$.25\mathrm{.}05C$

d$.$ None

e$.21\mathrm{.}05C$