Answer:
B. control rods and moderators
Because there is only one stable ionic compound made up of potassium and chlorine, and that is KCl. So calling is "mono chloride" or similar would be redundant assuming you understand basic chemistry (i.e. knowing oxidation numbers of K is +1 and Cl is -1). When compounds can exist in multiple forms in nature like CO and CO2 you will preferably indicate it through the nomenclature, calling one a monoxide and the other a dioxide.
Answer:
D
Explanation:
Protons and Neutrons both have a mass of about 1 amu so you add them but electrons have a mass of 0 amu so they are left out.