Answer:
d)
Explanation:
They're all countries except d)
During the early earth, when photosynthesis has not yet evolved, there were only negligible amounts of free oxygen in the atmosphere. It was said that the Earth's atmosphere had no free oxygen then. This is about 3.5 billion years ago.
Its C..please mark brainliest or at least 5 stars
This is an example of Positive reinforcement.
Positive reinforcement is the addition of a reinforcing stimulus (giving the dog a treat) following a behavior (rolling over), that makes it more likely that the behavior occurs again.
