Answer:
3,4, 5 and 6
Explanation:
There are four essential credits of natural selection –
a) Heredity – The genetic characteristics of an offspring are acquired by his/her parents. Parents while mating pass on the desirable of advantageous traits to their offspring for natural selection to act. Natural selection leads to variation and further changes in the advantageous traits based on the varying external and internal conditions.
b) Reproduction – Reproduction is very essential for natural selection or else the gene flow will stop. The larger is the gene flow, the larger is the gene pool thereby paving way for higher variations through natural selection
c) Variation in fitness – Not all species are fit to survive. Some have higher abilities to cope up with competitive pressure while some cannot cope up with the pressure of competition and hence die.
d) Variation in characteristics – Natural selection brings about changes in the genotype and phenotype of offspring. No two individuals are exactly similar. Variations is essential for progression of evolution.
Hence, option 3,4,5 and 6 are correct