The answer is D. Elevation.
The other three words, correction, improvement, and betterment, all refer to making something better. Elevation, on the other hand, refers to raising something to a higher level.
Correction is the act of making something right or accurate. Improvement is the act of making something better or more effective. Betterment is the act of making something better or more desirable. Elevation is the act of raising something to a higher level.
In the context of the question, the word that is different from the rest is elevation. The other three words, correction, improvement, and betterment, all refer to making something better. Elevation, on the other hand, refers to raising something to a higher level.