The correct answer is D. all of the above.
The tightness of clamping, gauge of laminations, and size of laminations all affect the degree of mechanical vibrations produced by the laminations of a transformer.
The tightness of clamping affects the amount of stress that is placed on the laminations. If the laminations are not clamped tightly enough, they will be able to move around more, which will cause more vibrations.
The gauge of laminations affects the thickness of the laminations. Thicker laminations will be less likely to vibrate than thinner laminations.
The size of laminations affects the surface area of the laminations. Larger laminations will have a greater surface area, which will make them more susceptible to vibrations.
In conclusion, the tightness of clamping, gauge of laminations, and size of laminations all affect the degree of mechanical vibrations produced by the laminations of a transformer.