The average temperature of first three days of the week is $$23^\circ C$$; the average temperature of next three days is $$24^\circ C$$ and the average temperature of whole week is $$23.5^\circ C$$. The temperature on the last day of the week is:

A

$$24.5^\circ C$$

B

$$22.5^\circ C$$

C

$$23.5^\circ C$$

D

$$21.5^\circ C$$