Edward Jenner inferred that a person who once had small pox cannot have it once again. So something is there in these persons which grows after the initial infection which interferes with the secondary infection resisting it.
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Explanation:</u></h3>
Edward Jenner is called the Father of Vaccination. Jenner noticed that the milkmaids who deal with the cows all the time don't generally suffer from the cowpox or small pox. Then as an Experiment, he took some sample from the pustules of the cow having pox and then cleaned it and injected the sample into a healthy child. Then when everyone of the locality suffered from the same disease, that child remained healthy. So that lead to infer that there are something in the pustule which lead to resist the secondary infection of this disease. So this lead to the invention of vaccines.
The variation may already exist within the population, but often the variation comes from a mutation, or a random change in an organism's genes.
Reproductive strategy is loosely used to refer to the way an animal mates and/or raises offspring
B. Thick Atmosphere
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Answer:
the magnetic direction of rocks along the surface of Earth and the age of rocks along the surface of Earth
Explanation:
The earth's magnetic field or geomagnetic field is believed to originate from the movement of molten iron and nickel in the outer core.
During a period in which the earth magnetic field is normal, crystallising magnetic minerals in magma records the orientation of the prevailing geomagnetic field. At other times when the field reverses and the magnetic field orientation changes, magnetic minerals in cooling magma stores this record.
To create a geomagnetic time scale, geologists can assign absolute ages to the records of these paleomagnetic anomalies which are the reversals. The rock is dated using radiometric techniques and each period of reversal is ascribed an absolute geologic age. Therefore, the magnetic direction of rocks along the surface of Earth and the age of rocks along the surface of Earth helps to build the geomagnetic time scale of the earth.
