$63)$ An unknown tuning fork is sounded along with a tuning fork whose frequency is $256.$ Hz and a beat

frequency of $3.$ Hz is heard. What is the frequency of the unknown tuning fork? $63)\_\_\_\_\_\_$

A$)$ It must be $259$ Hz$.$

B$)$ It could be either $253$ Hz or $259$ Hz; there is no way to tell.

C$)$ It must be $253$ Hz$.$

D$)$ It must be $256$ Hz$.$