1-C. You can get familiar with the area you're planning to visit by reading guidebooks and studying maps.You can get familiar with the area you're planning to visit by reading guidebooks and studying maps.
2-C. Guidebooks have been available for so long that most tourists do not need a tour guide.Guidebooks have been available for so long that most tourists do not need a tour guide.
3-C. not only in the long-established form of guidebooks but also through websites,not only in the long-established form of guidebooks but also through websites,