Idon’t get what it means by the trawler plunges and what are swells, i’m really confused on what to pick!

How does this excerpt develop the central idea that espionage during the civil war was often carried out by untrained citizens? it enhances the reader’s understanding by explaining why training was unnecessary. it changes the reader’s perception of what information a spy was able to obtain. it explains an ordinary person’s motivation for conducting espionage against the enemy. it adds moral complexity to espionage, due to the use of secret and dangerous methods.