Answer:
The researcher will need to limit the dependent variable to white bread or wheat bread.
Step-by-step explanation:
A dependent variable is one that is influenced by another variable, called an independent variable. In the case exposed in the question the dependent variable is fungal growth, this growth is influenced by the type of bread, since the fungal growth depends on the type of bread used by the researcher. The researcher should limit her assessment to one dependent variable and one independent variable at a time. Thus, we can conclude that what the researcher must do to accurately measure the dependent variable is to limit this variable to white bread or wheat bread.