I know this isn't answering your question but i think you will find it useful to visit the link pasted below. i just visited it and it explains pretty much everything about this.
A red blood cell's function is to transport oxygen.
Answer:
Explanation:
Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.
ORR
Struggle for existence, variation and inheritance. These are said to be the necessary and sufficient conditions for natural selection to occur.
Answer:
<h2>Option - C</h2>
<h3>Hope it helps you </h3>