Based on your description, wave A has a certain wavelength (distance between two consecutive crests) which is longer than that of wave B. Since wave B has a shorter distance between consecutive crests compared to wave A, this means that wave B has a shorter wavelength.
Additionally, frequency is inversely related to wavelength; therefore, if wave B has a shorter wavelength, it will have a greater frequency.
Thus, the correct completion of the statement is:
shorter wavelength and greater frequency.