Final answer:
The larger the receptive field, the stronger the stimulus intensity required to activate a sensory receptor.
Step-by-step explanation:
The larger the receptive field, the stronger the stimulus intensity required to activate a sensory receptor. When a receptive field is larger, it means that more primary sensory neurons synapse on a secondary sensory neuron, allowing for more sensory information to be received. However, it also means that fewer primary sensory neurons are involved, which can make it harder to perceive weaker stimuli.
For example, imagine two areas of the skin with different sizes of receptive fields. In the area with a smaller receptive field, it will take a stronger stimulus intensity to activate the sensory receptor because fewer primary sensory neurons are involved. On the other hand, in the area with a larger receptive field, a weaker stimulus intensity might be enough to activate the sensory receptor because more primary sensory neurons are involved.
Therefore, the correct answer is A. stronger the stimulus intensity required to activate a sensory receptor.