You observe your friend rub a balloon on their wool sweater and then stick it to the wall. To investigate, you set up an experiment to test whether other objects will respond in the same way when you rub them against a sweater. What is the test variable in your experiment? The number of times you rubbed the object on the sweater The observation that the object sticks to the wall The sweater you use to rub against the objects The type of objects you are testing in the experiment

The test variable is the type of objects.

Explanation:

You're using the same sweater, you're testing if it will stick to the wall in the same way, and you can rub it as many times as you want.

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.