Write the phrase in paragraph 3 that sets up a cause and effect relationship between rafting becoming safer and river ratings. Paragraph 3: Like most outdoor sports, rafting in general has become safer over the years. Expertise in the sport has increased, and equipment has become more specialized and durable. As a result, the difficulty rating of most river runs has changed. A classic example is the Colorado River in the Grand Canyon which historically has had a higher class ratings but low injury and fatality rates. Today the Grand Canyon sees hundreds of safe rafting trips by both "do it yourself" rafters and commercial whitewater rafting companies.