An increase in blood flow and a reduction in the resting heart rate

• Hypertension (chronic high blood pressure) increases the risk of strokes and heart attacks.
• Regular walking can help some people increase blood flow and decrease resting heart rate.
• Increased blood flow and a reduced resting heart rate can lower the occurrence of hypertension.

A. This is incorrect because the passage doesn't state that regular walking completely eliminates the risk of hypertension; it only says it helps reduce the occurrence for some people.

B. This is incorrect because the passage does not claim that people who don’t walk regularly are at a high risk of developing hypertension. It only states that walking can help reduce the risk for some people, but doesn't address the risk for non-walkers.

C. This is incorrect because the passage does not compare walking to other methods for improving blood flow and heart rate. It merely states that walking can assist some people.

D. This is correct. The passage explains that hypertension is a risk factor for strokes, and regular walking can help lower the occurrence of hypertension for some people, thereby lowering a risk factor for strokes.

E. This is incorrect because the passage does not state that walking alone is sufficient to lower the risk of heart attacks. Other factors may also play a role.

Answer D.