In an electrically neutral atom of any element, there are equal numbers of
a) protons and neutrons.
b) electrons and protons.
c) electrons and neutrons.
d) atomic number and atomic mass.
eliminate

B) Electrons and protons  

Explanation:  

Each proton has a positive charge, and each electron has a negative charge. If the atom is electrically neutral, there must be the same number of electrons and protons.

A) and C) are wrong. Neutrons have no charge, so they can't counteract that of the protons or the electrons.

D) is wrong. The atomic number is the number of protons, and the mass number is the number of protons plus neutrons. The neutrons can't  counteract the charge of the protons,

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.