J.J. Thompson is a British physicist who discovered the electron by a series of experiments which is designed to study the nature of a cathode ray tube. His discovery showed us that an atom can be split into smaller parts. He was a pioneer in the study of the model of an atom.
The answer is for sure A. Hope this helped!
Salt and water is a homogeneous mixture. Sand and water,salad dressing,soil are heterogeneous mixtures.