Final answer:
The basis of neural integration is the addition of postsynaptic potentials overlapping in time and space, a process known as summation that leads to changes in the neuron's membrane potential.
Step-by-step explanation:
The basis of neural integration is A. addition of postsynaptic potentials overlapping in time and space. This process, known as summation, occurs when multiple excitatory postsynaptic potentials (EPSPs) or a combination of excitatory and inhibitory postsynaptic potentials (IPSPs) add together at the axon hillock. When these postsynaptic potentials summate, they can lead to a significant change in the membrane potential. Summation can be either spatial, involving potentials that occur across different locations of the neuron's membrane, or temporal, where potentials occur at the same location but at different times. The result of this summation is the net change in membrane voltage that determines whether the neuron will reach the threshold to fire an action potential.