A sonometer wire vibrates in its fundamental mode and a tuning fork produces 5 beats per second with it. When the tension in the wire is slightly increased, the beat frequency falls to 2 beats per second. This shows that the frequency of the tuning fork is
(a) lower than the wire’s original frequency
(b) higher than the wire’s original frequency
(c) indeterminable from the given data
(d) equal to the average of the wire’s original and new frequencies