John Glenn was the first to orbit the earth
Answer:
A. Certified investment
Explanation:
I believe that this is why it gives the reader a certainty that it will work.
assuming efficiency of each man to dig trench, in one day, for one hour is constant,

so one man, working for one hour in one day can dig 1.5 m
so 8 men, working 3 hours a day and will take, say $d$ number of days and efficiency will be constant. so,
$\frac32=\frac{220}{8\times3\times d}$
$\implies d=\frac{55}9=6.12$
Answer:
D. because it allowed them to move west and yo move supplies and stuff to and from allowing for easier trade