Two spaceships $\backslash ($ A $\backslash )$ and $\backslash ($ B $\backslash )$ are moving towards each other along the same straight line. The approach speed of the ships is $\backslash (8000\backslash$mathrm$\{$~km$\}/\backslash$mathrm$\{$h$\}\backslash ).$ Every $10$ minutes a mail container is sent from ship $\backslash ($ A $\backslash )$ in the direction of ship B$.$ Containers move at a speed of $\backslash (12000\backslash$mathrm$\{$~km$\}/\backslash$mathrm$\{$h$\}\backslash )$ relative to a ship A$.$ How many containers does ship B receive in $1$ hour?

A$)4$

B$)9$

C$)10$

D$)30$