Answer:
The smallest possible beat frequency when B and C are sounded together is 3 Hz
Step-by-step explanation:
Given;
the beat frequency of A and B = 2 Hz
the beat frequency of A and C = 5 Hz
Beat frequency is equal to the difference in frequency of the two notes that interfere to produce the beats.

Therefore, the smallest possible beat frequency when B and C are sounded together is 3 Hz