What does the author mean by the phrase "build up"?

look it up...it will give u all the definitions of the word build up.

Explanation:

gradual or increases I typically of something Bad or negative and typically leading to a crisis . That is what at least in this case build up means .

c) troops march forward in close formation against newer, more accurate weapons

seeing as no choices were provided, i'll do my best to answer it from knowledge.

job specialization promotes work ethic to the person doing the job. he/she may be strong in the arms and able to lift things, specializing him/her in a job where you lift and carry.