hard parts are most likely to be preserved
The correct answer is frequency.
The pitch can be defined as the quality of sound produced by the rate of vibration producing it.
It is directly related to the the frequency of the sound wave. If the frequency is increased then its pitch will also increase and vice versa.
As for normal people it is a bit difficult to differentiate between the two but the musician are trained so they can differentiate the difference between the two even if the difference is 2 Hz
Natural selection refers to the phenomenon by which the species in a population possessing the tendency to get adapted in a condition enhance in numbers in comparison to those who exhibit fewer adaptation capacities over a number of generations.
In other words, it can be stated as the non-random and differential development of distinct genotypes function to sustain favorable variant and to eradicate less favorable variants. Some of the conditions are required for the process of natural selection to take place.
These are heredity, reproduction, variation in individual characters, and variation in the fitness of organisms among the members of the population. If the conditions are met, then the phenomenon of natural selection occurs by default.
