Which one of the following actions should the rescuer perform to aid a conscious casualty who is suffering a severe angina attack?

In the context of aiding a conscious casualty experiencing a severe angina attack, maintaining them in an upright position is the most appropriate action. This position helps alleviate the strain on the heart by reducing venous return, thereby decreasing myocardial oxygen demand, which is crucial during an angina episode.

When the casualty is upright, it can facilitate easier breathing and help manage chest pain more effectively. Additionally, staying upright may also help prevent potential complications such as fainting, which could occur if the individual were to lie flat and pressure is exerted on the heart.

Other actions listed would not provide the necessary support for managing an angina attack. For instance, administering glucagon is applicable in cases of diabetic emergencies, and initiating cardiopulmonary resuscitation (CPR) is meant for cardiac arrest situations, not angina. Laying the casualty flat could increase discomfort and exacerbate the condition, making their situation less stable. Thus, keeping the casualty upright aligns with best practices for managing an acute angina episode.