angle of tilt of the table acidity of the water amount of sediment eroded rate that sediment is eroded
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A student wants to use a stream table to test the influence of water acidity on the erosion rate of a stream. Which variable should be constant in this experiment?
Possibilities:
- angle of tilt of the table
- acidity of the water
- amount of sediment eroded
- rate that sediment is eroded

angle of tilt of the table