50%
Assuming that the coins are fair and each have a 50% chance of
head or tails there are 4 equally likely combinations that can occur:
first coin is a head and second is a head, first a head and second a
tail, first a tail and second a head, first a tail and second a tail.
Each is as likely, 25%. The four choices are HH, HT, TH, TT, and you
can see that two of them (HT, TH) fulfill having one head and one tail,
giving you 25% +25% making is 50%.
<span>Other factors found within its environment can make pioneer species still germinate and thrive. Factors like wind, presence of animals, rain, among others, can help in the germination of the pioneer species even if its immediate environment becomes inhospitable through time.</span>
I think it might be Stratosphere, if Ozone layer is an option I will suggest that too.
