According to the text, physical exercise in late adulthood encourages the birth of new neurons in areas responsible for learning and memory. in other words, exercise facilitates in the

Physical exercise in the late adulthood facilitates neurogenesis in the hippocampus.

Explanation:

Physical exercise is always a better thing; it makes you healthy and fit. Especially in adulthood, it helps in increasing the memory and learning capacity by facilitating the neurogenesis. It helps in nervous system to produce NCS neutral stem cells. Neurogenesis is the process that continues in the adulthood, so by the physical exercise one can enhance this process for better memory power and good learning abilities.

Ibelieve that the answer is (a).