They could improve the experiment that they made by adding another variable such as: watering the plants with fresh water. This way they could have a better comparison how plants grow based on the type of water they are exposed with.
The Answer is B i just took the test. Enjoy, i also just looked it up on a quizlet. That's another website you can use if it comes up in the search for the question.
Answer:
I think the answer is capital
A sound wave is A wave of compression and rarefraction .
