With reference to the passage, the following assumptions have been made:<br/>1. Only species that have the ability to overcome environmental catastrophes will survive and perpetuate.<br/>2. More than 90% of the species on the earth are in the danger of getting extinct due to drastic changes in the environment.<br/>3. Darwin's theory explains all the natural phenomena.<br/><br/>Which of the above assumptions is/are valid?

1. Valid. Natural selection implies that species able to adapt to or withstand environmental changes are more likely to survive and continue.

2. Not valid. The claim that more than 90% of species are currently in danger of extinction is an extreme and unsupported assumption; no such accepted fact follows from Darwinian reasoning.

3. Not valid. Darwin's theory explains biological evolution by natural selection, not all natural phenomena.

Therefore, only statement 1 is a valid assumption.