A) Erie Canal is the answer
Do some note cards and write the question from the front and the answer on the back then try to remember what’s on the card hope that helps
Answer:
The control of malaria was vital for the construction of the Panama Canal. The discovery by Major Ronald Ross that malaria was transmitted by mosquitoes had tremendous impact on development programs in the tropics
Explanation:
I believe the answer is: You must not proceed until you are sure there are no other trains approaching on any of the tracks.
Crossbuck signs is put to indicates that there could be more than one train that can pass within a short time period. The maximum number of train could be up to 3 , so you need to make sure that there are no other trains approaching to avoid collisions.