The correct answer is letter C
LTP is the most recognized cellular mechanism for explaining memory, because it can alter the strength between brain cell connections. If this strength is maintained, a memory can be formed.
Long-term potentiation happens when the nerve cells "shed" or speak to one another at a high rate, without increasing the stimulation of neurotransmitters. In a sense, it's like building a relationship with the email sender. Once you have started a dialogue with the sender you are in a better position to communicate more easily and maintain a strong relationship. Just as you can add the sender to your contact list, your brain has created an “enhanced synaptic contact.” But, if you are not speaking, the relationship decreases.