Is it true or false that there are three types of cones each of which is maximally sensitive to a different wavelength?

True. The human eye has three types of cones, each one being most sensitive to a different range of wavelengths. These are typically referred to as short-wavelength (S-cones), medium-wavelength (M-cones), and long-wavelength (L-cones) cones, covering the blue, green, and red regions of the visible spectrum, respectively.