Final answer:
Rats with hippocampal lesions are the ones that do worse in finding a platform in a water pool, as the hippocampus is essential for spatial memory and navigation.
Step-by-step explanation:
The correct answer to the question about which type of lesions would result in a rat doing worse in finding a platform in a water pool is:
(A) Hippocampal lesions.
The hippocampus is critically involved in memory and navigation, including spatial memory and learning. Damage to the hippocampus can impair the ability to form new memories and can diminish the capacity to navigate through space, which would likely make it difficult for rats to learn and remember the location of a platform in a water maze. This task is often used in research to assess spatial learning and memory in rodents.
It should be noted that the amygdala, thalamic, and basal ganglia structures play different roles in emotional responses, sensory processing, and motor control respectively, but they are not primarily responsible for spatial learning in the context of this specific water pool platform task.