The number of protons of an element will always refer to its identity in the periodic table, for example we have the element with number of protons = 1, this is also the identity of a Hydrogen atom. Usually in neutral elements, the number of electrons will match the number of protons, but when we have ions, the number of electrons will be higher or lower than the number of electrons, and we also can identify these ions placing numbers, positive and negative symbols. For our question we have:
A) 3 protons and 2 electrons = Lithium ion or Li^+
B) 9 protons and 10 electrons = Fluorine ion or F^-
C) 12 protons and 10 electrons = Magnesium ion or Mg^2+
D) 26 protons and 23 electrons = Iron ion or Fe^3+