Which of the following remedies is used for treating coughs?

Gugel mugel is traditionally used as a remedy for treating coughs. It is a type of herbal mixture that may contain various soothing ingredients aimed at relieving throat irritation and coughing. Historically, such remedies have been derived from natural ingredients, showing cultural practices in managing respiratory symptoms.

The other options represent remedies or objects that do not have a historical or cultural basis for effectively treating coughs. Swamp root, while used for other conditions, is not specifically known for treating coughs. A hard knife is an inanimate object without any medicinal properties, and spider webs do not have therapeutic applications for cough treatment, despite some folklore suggesting otherwise.