In humans, sickle-cell anemia is caused by an allele that results in abnormal hemoglobin that sickles red blood cells in certain situations. individuals who are heterozygous for normal and sickle-cell alleles are protected from malaria; homozygous normal has no protection and homozygous sickle-cell has symptoms such as low tolerance for exertion and a shortened life span. this is an example of

This is an example of balanced polymorphism.  This occurs when the heterozygous individuals persist in a population because homozygous individuals are less able to survive compared to the heterozygous individuals. In the case of sickle-cell anemia, individuals with two copies of the β-globin sickle-cell allele develop sickle-cell disease and generally don't survive into adulthood, whereas individuals with one copy of the β-globin sickle-cell allele and one β-globin wild-type allele have functional red blood cells that are also resistant to malaria. We can expect this example of balanced polymorphism to occur in areas prone to malaria.  

rocks and weathering-matching

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.