Answer:
D. 17 years
Explanation:
if you were in 2004 cicadas were around that time. 2004 to get to 2021 is 17 years so its D
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Manipulated Variable:The speed working on maths problems
Responding Variable: The group that use¬ using a calculator
Controlled Variable:The same maths quetions
The type of soil varies from place to place on our planet and can even vary from one place to another in your own backyard. Soil erosion, caused by wind and rain, can change land by wearing down mountains, creating valleys, making rivers appear and disappear.
Answer: Four pulmonary veins.
Explanation: Oxygen and nutrient rich blood will flow from the lungs back into this part called the left atrium (Or as some will call it, the left upper chamber in the heart). From there, it goes through four pulmonary veins.
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Trichomes increase the chances of survival for plants living in areas with infrequent rainfall.
If a plant in a very rainy place had trichomes, it would probably adapt and remove them as time passed as they are unnecessary.