The organisms which appeared on earth first was bacteria.
<u>Explanation:</u>
- The first-ever living organism on Earth was a bacteria known as cyanobacteria. It is believed by scientists that it first formed around 3 billion years ago.
- When the Earth was first formed, it was inhospitable for a long time until 3.8 billion years ago approximately, the core cooled down and the level of oxygen had risen. This, along with photosynthesis resulted in the formation of Cyanobacteria.
- These organisms were capable of carrying out the process of photosynthesis by which they prepared their food. These were known as common ancestors. All the living organisms thereafter are known to be their descendants.
The answer is the first one
Moves astronauts around
The correct answer to the question stated above is the first option: <span>an instinctive behavior was tied to a different stimulus.
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Pavlov's experiment was a typical case of classical conditioning because an instinctive behavior was tied to a different stimulus.
