Which of these magnets is most likely a permanent magnet?

The obvious answer would be Magnet A.

Explanation:

Because it shows in the middle box it say's It is not really magnetized but retain's it's magnetic properties for a long time. it cannot be the others cause Magnet B. doesn't have any information about it being permanent and Magnet C. say's that it is just not magnetized.

temp rises, and expansion

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

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