Read the follwing passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions. Niagara Falls, one of the most famous North American natural wonders, has long been a popular tourist destination. Tourists today flock to see the two falls that actually constitute Niagara Falls: the 173-foot-high Horseshoe Falls on the Canadian side of the Niagara River in the Canadian province of Ontario and 182-foot-high American Falls on the U.S. ...

Read the follwing passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.

Niagara Falls, one of the most famous North American natural wonders, has long been a popular tourist destination. Tourists today flock to see the two falls that actually constitute Niagara Falls: the 173-foot-high Horseshoe Falls on the Canadian side of the Niagara River in the Canadian province of Ontario and 182-foot-high American Falls on the U.S. side of the river in the state of New York. Approximately 85 percent of the water that goes over the falls actually goes over Horseshoe Falls, with the rest going over American Falls.

Most visitors come between April and October, and it is quite a popular activity to take a steamer out onto the river and right up to the base of the falls for a close-up view. It is also possible to get a spectacular view of the falls from the strategic locations along the Niagara River, such as Prospect Point of Table Rock, or from one of the four observation towers which have heights up to 500 feet.

Tourists have been visiting Niagara Falls in large numbers since the 1800’s; annual visitation now averages above 10 million visitors per year. Because of concern that all these tourists would inadvertently destroy the natural beauty of this scenic wonder, the State of New York in 1885 created Niagara Falls Park in order to protect the land surrounding American Falls. A year later Canda created Queen Victoria Park on the Canadian side of the Niagara, around Horseshoe Falls. With the area surrounding the falls under the jurisdiction of government agencies, appropriate steps could be taken to preserve the pristine beauty of the area.

The word “flock” in paragraph 1 could best be replaced by ________.