What characterizes a hawser in terms of its size?

A hawser is characterized as a flexible line that is usually over 5 inches in circumference, making option B the correct choice. Hawsers are designed to carry heavy loads and are typically used for towing or mooring larger vessels, which necessitates their larger diameter for strength and durability.

The other options do not accurately capture the defining characteristics of a hawser. For instance, hawsers are not always lightweight; in fact, their thickness and the materials used make them robust and capable of handling significant stresses, contradicting the notion of being lightweight. Additionally, while hawsers must indeed be strong, they are usually not under 1 inch; rather, they exceed this size to cope with the demands of marine applications. Lastly, hawsers are utilized in various maritime contexts, including large vessels, rather than being limited to small boat applications, further emphasizing their versatility in marine operations.