Final answer:
The M-mode findings for aortic valve stenosis include reduced leaflet separation in systole, thickening of the aortic valve leaflets, and diastolic flutter.
Step-by-step explanation:
The characteristic M-mode findings for aortic valve stenosis include reduced leaflet separation in systole, thickening of the aortic valve leaflets, and diastolic flutter of the aortic valve leaflets. Therefore, the correct answer is A. A lack of systolic flutter of the aortic valve leaflets. In aortic valve stenosis, the narrowing of the valve opening obstructs the blood flow and leads to the mentioned findings.