Final answer:
Memory formation is associated with the (c) release of certain neurotransmitters.
Step-by-step explanation:
The research by Kandel and Schwartz on sea slugs indicates that memory formation is associated with the release of certain neurotransmitters.
According to the information provided, the addition of serotonin to the tissue culture of sea slugs increases the number of synaptic connections, which can induce training and memory formation. Communication among neurons via neurotransmitters is critical for developing new memories, and repeated activity by neurons leads to increased neurotransmitters in the synapses and more efficient synaptic connections, facilitating memory consolidation.