What is the correct developmental sequence

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

Along what geographical feature are most of the oil producing regions located

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled