The main reason it's important to only test one variable at a time is so that?

a. qualitative data can be recorded

b. scientists can easily tell which variable caused the results

c. scientists can have many hypotheses tested at once

d. quantitative data can be recorded

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit