Researchers control factors such as age or attitudes that might influence a dependent variable by means of:a) operational definitions. b) naturalistic observation. c) replication. d) random assignment.

The correct answer to the following question is D) random assignment.

Explanation:

Random assignment which also know as random replacement, can be defined as an experimental technique where either human participants or animal subjects are assigned to different groups in an experiment by using randomization or random number generator. By doing this it is ensured that each participant has equal chance of being placed in a random group.