Answer the following question: Read the article and select the best answer. Article: Nearly 60 million visitors flooded to the 384 national parks across America every year. And you won't have to wander far from home to enjoy one of these national treasures, with Michigan's Isle Royale National Park nearby. Located 56 miles from Copper Harbor on Michigan's Upper Peninsula, the park remains _ that can only be reached by tour boat. With the exception of the Rock Harbor Lodge, which offers both rooms with private baths and accommodations in the form of small cottages, the 572,000 acres that make up the 45-mile-long park are rough, threaded with hiking paths that lead to tents-only campsites. You are likely to see a deer crossing mist-covered ponds in search of breakfast, gaze bald eagles flying overhead, or hear a beaver clapping its tail on the water. If you are especially lucky, you might even glimpse a grey wolf, nearly dying out from hunting on the mainland. Plenty of hiking paths open the area to exploration. The 4-mile Stroll Path winds through various trees and offers a tour of the island's history, including prehistoric Indian mines. The Jungle Path leads to Scoville Point----a perfect picnic spot surrounded on three sides by the shining waters of Lake Superior. You can also rent a boat at the park's service center and row down the shore to the Rock Harbor Lighthouse. Here park's service employees use nets to show how lake fishes used to be caught by the original local people. Their catch ends up on the dinner menu at the Rock Harbor Lodge. The park is open from mid-April through October; Rock Harbor Lodge is open from Memorial Day weekend until just after Labor Day. Question: What is the main idea of the passage? Options: A: Safety tips of the natural park. B: Attractions of the natural park. C: Tourist service of the natural park. D: Environmental protection of the natural park.
Answer:
B