We therefore can calculate that the total energy the sun has to burn is around 1.3 x 1044 Joules. Dividing 3.8 x 1026 Watts (the rate at which the sun is giving off energy) into this number gives an approximate value of 10 billion years for the sun's lifetime.
I believe the answer is retrovirus
option B both sexually and asexually
Explanation:
Algae regenerate by sexual reproduction, involving male and female gametes (sex cells), by asexual reproduction, or by both ways. Many small algae reproduce asexually by ordinary cell division or by fragmentation, whereas larger algae reproduce by spores. ...
There were more organisms born than resources can support.
And this led to struggles between organisms and later only the fittest animal survived :)
