To investigate a possible relationship between two factors, such as acidity and solubility, you must first identify the variables involved in the experiment. Identify the independent variable, the dependent variable, and any possible confounding variables within this experiment.

answer: a. exercising often and eating a balanced diet.

explanation:

if he does not use open the compass the a width greater than half of po, he will not be able to find the midpoint of the line, without the midpoint of the line, he will not be able to bisect the line.   to find the midpoint of a line the circles drawn with a compass must either intersect or be touching.