As possible sites for a canal, what do mexico, costa rica, panama, and colombia have in common?

The countries of Mexico, Costa Rica, Panama, and Colombia, are all countries that have excellent locations for building canals that would contribute to much easier sea travel and trade, and cutting of on distance significantly. This is because all four countries are countries that have access on two large water bodies, on the eastern side that is the Caribbean Sea, and through it a direct connection with the Atlantic Ocean, and on the western side it is the Pacific Ocean. Still, so far, only one of them have been chosen for a canal, and that is Panama, and this was mainly due to the lowland relief and because the country has the smallest land mass between the two water bodies.

the confederate at bull run

i believe the correct answer is b.