An experiment can show: OA. how changing a variable can affect behavior.
O B. how observations can be valid.
OC. wording bias.
OD. interviewer bias.

A. how changing a variable can affect behavior.

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).

Hence, an experiment can show how changing a variable can affect behavior.

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.