This question isn't really finished, but bacterium are unicellular prokaryote.
I hope this helps?.. :S
Answer:
I think it is C if I am wrong i am srry
Methane is the gas that is strongly correlated with Earth's heating and cooling patterns. Did you know that cow's flatulence is methane gas?! Interesting fact!
Visual disturbance is the most likely to precede primary succession
The correct answer is -
E. double coincidence of wants