Its stabilising. Since the selection pressure is against the extremes which are the normal blood and the sickle cell anaemia.
The 3rd one I think not really sure
A biological theory, like the theory of evolution, that is widely accepted and supported by so many observations and experiments may be referred to as a principle or a law.
<h3>What is a Law?</h3>
This refers to statements which describes or predict a range of natural phenomena as a result of repeated experiments which has been performed and the authenticity has been prove by peers and other individuals.
A law is also referred to as principle and has been observed to be always true unlike due to the repeated scientific methods being done approving of its validity thereby making law the correct choice.
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"Since taking control, britain had made laws that imposed harsh taxes and stopped indian trade with other countries."