Which of the following was the independent variable in this investigation? A - HSC - SSCE Biology - Question 10 - 2022 - Paper 1

In an investigation, the independent variable is the factor that is intentionally varied or manipulated by the researcher to observe its effect on the dependent variable. In this context, we need to determine which option represents the independent variable.

The air, flask, broth, and microbes all play a role in the investigation, but one option specifically represents the factor that was changed to see how it affects the outcome.

Considering the nature of experiments where conditions are adjusted to assess the growth of microbes, the independent variable involves the containers or flasks used to hold the broth that could influence microbial activity. Therefore, the correct answer is B: The flask.