Final answer:
Rebalancing the humours, an ancient medical practice, was historically achieved through diet and lifestyle changes, in line with option A. This could involve eating certain foods and altering physical activity. Other mentioned methods are not historically documented for this practice.
Step-by-step explanation:
The concept of rebalancing the humours originates from an ancient medical theory that suggested the human body is governed by four humours: blood, phlegm, yellow bile, and black bile. An imbalance in these humours was thought to cause illness. To rebalance the humours, option A) Through diet and lifestyle changes is historically accurate. Methods such as eating various foods that were thought to counteract an excess of a certain humour, or changing one's level of physical activity were recommended. Techniques such as meditation by sitting upright in a comfortable chair, being in a quiet environment, repeating a mantra like “alert mind, calm body,” and focusing on pleasant thoughts could potentially support mental wellbeing, though this is not directly related to the historical practice of humour rebalancing.
While exposure to sunlight and blood transfusions could theoretically impact one's health, they were not methods historically associated with humour rebalancing. Similarly, reciting specific chants is not documented as a method for correcting humoral imbalances. Instead, maintaining a balanced diet and modifying lifestyle choices are closer to the historical recommendations for manipulating one's humoural balance.