Dan wants to test the effects of different amounts of antibiotic on bacteria. While setting up his experiment he makes sure to use the same type of antibiotic, the same type of bacteria, and the same type of incubator for each trial. Which phrase below best describes this part of the experiment?

C

Explanation:

A. analyzing results

B. collecting data

C. choosing controlled variables

D. making a prediction

The correct answer would be choosing controlled variables.

The controlled variables are factors that are kept constant among the different groups of subjects during the course of an experiment so as to be able to isolate the effects of a single factor - the independent variable.

There are basically 3 types of variables in a scientific experiment;

1. The independent variable

2. The dependent variable

3. The controlled variable

The independent variables are the variables whose effects are to be determined in the course of experiments. The dependent variables are the variables that are actually measured during the course of experiments and whose values vary along with that of the independent variables. The controlled variables are other variables required for the experiment but which must be kept constant among subjects in order to be able to isolate the effects of the independent variable.

The correct option is C.

sodium (na), for example, has one electron in its valence shell. this is an unstable state because that valence shell needs eight electrons to be full. in order to fill its valence shell, find a way to add seven electrons to its valence shell