1. Testing only one variable
A controlled variable means its the one that stays the same. In a controlled experiment, it means there is only one manipulated, (changed) variable.
Answer:
That is administered and controlled
Step-by-step explanation:
A variable is the condition or a product that may vary without the influence of any investigator. Such variables can be found abundantly in our daily lives, ranging from air to sunlight. Controlling such variables ensures the limitation of their influence on the outcome of an experiment. In connection to this experiment, the variables that are controlled are the mineral content in the water, the amount of bacteria food, the amount of light and the the constant temperature of 20 degrees C.
If not administered or these variables controlled, the experiment would not clearly explain the impact of caffeine on the heart beat of the water fleas as other variables may have influenced it. Thus variables are controlled to study the singular impact of any agent or effect.
Glacial evidence discovered in South America demonstrates how climate change evidence has bolstered the notion of continental drift. Folded mountains in Africa and South America. Thus, the correct option is D.
Climate change is happening all across the planet on a daily basis. This is primarily due to human activities that have had an impact on the atmosphere and the earth.
<h3>
What is continental drift?</h3>
Continental drift is basically the hypothesis that the continents once constituted a single landmass, disintegrated, and drifted to their current places.
The discovery of glacial evidence in South America has led to a greater acceptance of the continental drift idea.
Finally, we can conclude that glacial evidence discovered in South America demonstrates how climatic change evidence supports the hypothesis of continental drift.
For more information regarding continental drift, visit:
brainly.com/question/974409
#SPJ1
30% of the earth's surface is covered by forests.
----------------------------------------------------------------------------------------
