Which of these is an example of how engineers have contributed to society? A. Our current understanding of viruses
B. The seven-mile bridge that spans across the Gulf of Mexico to
connect two cities of the Florida Keys
C. Nomadic tribes traveling in search of food to hunt and gather
D. The theoretical mathematics describing the orbits of planets
around the sun

B.

Explanation:

One of the biggest examples of engineers' contribution to society is they link different communities together through transport infrastructure.

The seven-mile bridge was an engineering wonder. Seven Mile Bridge connects two cities of the Florida Keys that include Knight's Key and Little Duck Key and promotes the transportation of goods or several other services which was not possible at that time (1900s).

It is the longest bridge in the world and is constructed by using the “segmental” technique and engineers were acknowledged for their work.

Hence, the correct option is B.