A nurse is attending a social event when another guest coughs weakly once, grasps his throat with his hands, and cannot talk. Which of the following actions should the nurse take?

The correct answer is B: Perform the Heimlich maneuver. This is the appropriate action for a choking individual who is coughing weakly, grasping their throat, and unable to talk, indicating a partial airway obstruction. The Heimlich maneuver helps clear the airway by applying abdominal thrusts to expel the obstructing object. Observing the client (A) may lead to a worsening situation. Slapping the client on the back (C) can be ineffective and potentially harmful. Assisting the client to the floor for mouth-to-mouth resuscitation (D) is not indicated for a conscious choking individual.