A 75-year-old woman with hypertension develops fatigue and dyspnea on exertion. Her blood pressure is 160/60 mm Hg and pulse 80/min. The second heart sound is diminished and there is an early diastolic murmur that radiates from the right sternal border to the apex. Your clinical diagnosis is aortic regurgitation.For the above patients, select the characteristic arterial pulse finding.