Correct Answer (Detailed Explanation is Below)
A.
Anders Jonas Ångström
Detailed Explanation
Anders Jonas Ångström was a Swedish physicist and astronomer associated with spectroscopy and the study of solar spectra. The unit
angstrom (Å) was named in his honour. It is particularly useful for expressing wavelengths and microscopic distances. Spectroscopy remains an important application of wavelength measurement in physics and chemistry.