• Color file negatives or x-ray film with pictures on it.

•  smoked glass, photographic polarizing filters or neutral density filters 

•  None of the above.

To safely view the sun directly, don't use your sunglasses! Use only filters designed for that purpose, such as aluminized mylar or a number 14 welder's glass. Better yet, use a pinhole in aluminum foil to project the image of the sun on a white piece of paper placed a half meter or so behind it. Placing the pinhole over a hole in the top of a box, taping the white paper to the inside bottom, and cutting a view window in the side will provide a brighter image, shielded from the outside light.  

While it is true that staring at the sun during the partial phases of a solar eclipse without eye protection may cause eye damage or blindness, the physical danger is no greater than staring at the sun during any other time.  

Despite all these warnings, the beauty of the TOTAL phase of the eclipse (when the sun is completely covered by the moon) can be and should be enjoyed without using any filters whatsoever!