Reading comprehension II term.

Every year about two million people visit Mount Rushmore, where the faces of four U.S. presidents were carved in granite by the sculptor Gutzon Borglum and his son. The creation of the Mount Rushmore monument took 14 years - from 1927 to 1941 - and nearly a million dollars. These were times when money was difficult to come by, and many people were jobless. To help him with this sculpture, Borglum hired laid-off workers from the closed-down mines in the Black Hills area of South Dakota. He taught these men to dynamite, drill, carve, and finish the granite as they were hanging in midair in his specially devised chairs, which had many safety features.
Borglum used dynamite to remove 90 percent of the 450,000 tons of rock from the mountain quickly and relatively inexpensively. His workmen became so skilled that without causing damage, they could blast to within four inches of the finished surface and grade the contours of the facial features. Borglum was proud of the fact that no workers were killed or seriously injured during the years of blasting and carving the granite. Considering the workers regularly used dynamite and heavy equipment, this was a remarkable feat.
During the carving, many changes in the original design had to be made to keep the carved heads free of large fissures that were uncovered. However, not all the cracks could be avoided, so Borglum concocted a mixture of granite dust, white lead, and linseed oil to fill them.
Every winter, water from melting snow gets into the fissures and expands as it freezes, making the fissures bigger. Consequently, every autumn maintenance work is done to refill the cracks. To preserve this national monument for future generations, the repairers swing out in space over a 500-foot drop and fix the monument with the same mixture that Borglum used.

Оберить правильну відповідь.

The author of the passage indicates that the men Borglum hired were

According to the passage, what achievement did Borglum pride himself on?

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.