Which is an example of eugenics?

the science of improving a human population by controlled breeding to increase the occurrence of desirable heritable characteristics.

the difference is that white collar worker performs skills like worker as a scientist or well blue collars do physical work and they do services like being a cook.

the causes of the dust bowls were severe droughts,   lands became dry and hard, temperature was higher than usual, hot and dry conditions killed crops, high winds. because of those factors, the winds kicked up dry soil and created clouds of dust.