Final answer:
The reason that best supports Lucas' claim is that exercise improves student health and school performance.
Step-by-step explanation:
The reason that best supports Lucas' claim that an hour of physical education should be included in every student's school day is that exercise improves student health and school performance. Physical exercise has been shown to reduce risk factors for cardiovascular disease, such as hypertension and excess body weight. It can also increase cardiovascular health factors, such as the mechanical efficiency of the heart. Additionally, regular aerobic exercise has been found to be effective in treating mild-to-moderate depression.