When the student moves closer while continuing to create a wave on the jump rope, the frequency of the wave will increase due to the increased speed of the wave source.
Since the wave is moving through the same medium (the jump rope), the speed of the wave will remain constant.
The wavelength is inversely related to frequency (as per the wave equation: \( v = f \lambda \), where \( v \) is speed, \( f \) is frequency, and \( \lambda \) is wavelength). Therefore, if the frequency increases as the student moves closer, the wavelength must decrease.
So, the correct answer is wavelength.