Answer:
a. confounding variables.
Step-by-step explanation:
An experiment can be defined as an investigation which typically involves the process of manipulating an independent variable (the cause) in order to be able to determine or measure the dependent variable (the effect).
This ultimately implies that, an experiment can be used by scientists to show or demonstrate how a condition causes or gives rise to another i.e cause and effect, influence, behavior, etc in a sample.
In an experiment , the variable being manipulated by an experimenter is known as an independent variable while the dependent variable is the event expected to change when the independent variable is manipulated.
A confounding variable can be defined as a variable that generally influences both the independent and dependent variable in an experiment or research study. Thus, it creates an association between the two variables in an experiment.
Hence, when conducting research, confounding variables are unintentional factors that creep into your experiment and have the potential to affect or even spoil your results.