Answer:
Valence electrons or outer electrons are most important as they participate in bonding. The octet rule states that atoms gain, lose, or share valence electrons to have filled energy levels.. this gives atoms a stable configuration like that of the nearest noble gas.
The answer is D transition state. In the energy profile, the transition state is the highest point. For a reaction, the activation energy is the minimal energy needed to trigger a reaction. The reactants are the start of the reaction and the products are the end of the reaction.