Spencer’s blog claims that national parks are the best vacation destinations. Which evidence is best for developing his claim?
A
a personal account from a park visitor who describes positive adventures at Grand Canyon and Yellowstone parksB
an interview with a travel agent who advertises cruises, eco-tours, and whitewater rafting tripsC
a chart that compares the number of national parks in the eastern United States to that in the western statesD
a study that proves adults who take yearly vacations have lower blood pressure than those who do not