Once workers began the "make the dirt fly" strategy, what slowed the project down?

The total soil excavated from the Panama Canal would build a pyramid 4,200 feet high.  The project consumed as much as twelve million pounds of dynamite per year.  At the hight of the project, 9,000 workers were busy excavating Culebra Cut.

On August 15th, 1914, the Panama Canal opened, connecting the world’s two largest oceans and signaling America’s emergence as a global superpower. American ingenuity and innovation had succeeded where, just a few years earlier, the French had failed disastrously. But the U.S. paid a price for victory.

The words “Make The Dirt Fly” were used by president Theodore Roosevelt to Chief Engineer, John Findley Wallace, who was designated by Teddy Roosevelt to build the Panama Canal after the French had failed.  Teddy was interested in getting the ditch built immediately.  He wanted dirt to fly in Panama and it did.

Rear Admiral Walker, President of the Panama Canal Commission, received a telegram to-day from John Findley Wallace of Chicago, General Manager of the Illinois Central Railroad, accepting the appointment of chief engineer in charge of the construction of the Panama Canal. Mr. Wallace would receive a salary of $25,000 a year.

d) all choices are correct