题目选项分析

The physical structure of the human eye enables it to sense light of wavelengths up to 0.0005 millimeters; infrared radiation, however, is invisible because its wavelength - 0.1 millimeters - is too long to be registered by the eye.

The physical structure of the human eye enables it to sense light of wavelengths up to 0.0005 millimeters; however because the wavelength of infrared radiation is 0.1 millimeters, it is too long for the eye to register and thus invisible.