Final answer:
The frequency of tuning fork B is 344 Hz because it produced 5 beats per second when paired with a 341 Hz fork, and 3 beats per second once its mass was increased, indicating the frequency was originally higher than 341 Hz and got closer to it after adding wax.
Step-by-step explanation:
When tuning fork A with a frequency of 341 Hz is sounded with tuning fork B and they produce 5 beats per second, the frequency of tuning fork B must be either 346 Hz or 336 Hz, because the beat frequency is the absolute value of the difference between the two frequencies. When wax is applied to one of the prongs of tuning fork B, the mass increases, causing the frequency to decrease. This results in 3 beats per second instead of 5, which means the frequency of B has come closer to 341 Hz. Since adding mass to the fork would lower the frequency, tuning fork B's initial frequency before adding wax must have been higher than that of A, suggesting a frequency of 346 Hz originally. After adding wax, the frequency of B decreased, yielding 3 beats per second with tuning fork A, thus giving tuning fork B a frequency of 344 Hz after applying the wax. Therefore, the correct answer is (a) 344 Hz.