The tone of the passage is informative, as it presents information about the benefits of regular physical activity in a clear and educational manner. It uses objective language to explain how exercise impacts mental and physical health, supported by scientific references, such as "Studies have shown that exercise releases endorphins, chemicals in the brain that act as natural painkillers and mood elevators." The passage aims to educate the reader without emotional exaggeration, criticism, or humour, making "informative" the most fitting description of its tone.
Critical: The passage does not criticize any aspect of exercise or related practices. It presents benefits in a positive, non-judgmental way, lacking the analytical or fault-finding tone associated with criticism.
Dramatic: The passage avoids exaggerated or emotionally charged language. It uses a calm, factual approach rather than dramatic expressions to convey its message.
Humorous: There is no humour or light-heartedness in the passage. The language is serious and focused on providing information, with no playful or comedic elements.
Hence, the correct answer is option (a).