A tow of 9 barges is made up three abreast by three long. The towboat is faced up to the last barge of the center string. The outer two strings of barges are the __________.

Correct Answer: Option C — drag strings

In a three-by-three barge tow configuration, the center string is directly connected to the towboat. The outer strings, which are not directly connected to the towboat's pushing gear, are referred to as drag strings. These strings rely on the tension and connection to the center string for movement.