Final answer:
The receptive portions of a neuron are the dendrites and the soma (cell body), as they are responsible for receiving and integrating signals.
Step-by-step explanation:
The receptive portions of a neuron are the parts that receive signals from other neurons. These include the dendrites which are the main signal receivers of a neuron, as well as the soma (cell body), which integrates the signals. The axon hillock, while it plays a crucial role in the neuron's activity by integrating the incoming signals and initiating the nerve impulse, is not typically classified as a receptive structure. Therefore, the answer to the question is a and c - dendrites and soma (cell body).