i think its B)... im not sure so dont take it seriously
It will be 3 wavelengths because 1 cycle = 1 wavelength.
A. K20 is the correct answrr
That's the <em><u>speed</u></em> of the wave.
("Velocity" is not a good way to say it, because 'velocity' always needs a direction,
and neither frequency nor wavelength tells anything about direction.)