Which is correct?

"More than 3000 years ago, an ancient king of Egypt ordered that a river be built to connect the Mediterranean Sea with the Red Sea. This kind of man-made river is called a canal. Ancient evidence shows the work was done and a canal was built. Experts believe it was possible for small boats of that time to travel from the Mediterranean Sea to the Red Sea. Some evidence shows the Nile River may have been used for part of the canal. However, the ancient people of Egypt did not keep this canal in use. As years passed, the sands of the great deserts of Egypt covered the small canal. As the centuries passed, many people thought it would be a good idea to rebuild the canal. The problem was the huge cost, but the cost wasn't as high as that of a ship that had to sail from ports on the Atlantic Ocean to the ones in Asia."
A- building a canal was thought to be impossible because of the distance between the Mediterranean Sea and the Red Sea
B- the idea of a canal to connect the Mediterranean Sea and the Red Sea was thought long before the construction of it.
C- the project for a canal between the Mediterranean Sea and the Red Sea couldn't be funded by the ancient Egyptians.
D- the canal by the ancient Egyptians was much longer than the one built in the 20th century.
E- the canal between the Mediterranean Sea and the Red Sea was constructed at a low cost.
I said C. But the answer is B. I couldn't understand it. Can you explain why it is B?