A. They invented writing materials that allowed for the easy correction of mistakes
It would be popular vote ,well thats what they clam xD
Answer: Regression-artifact
Explanation:
Regression artifact is the process in which non- random samples that represent the population is selected along with defective correlation with each other .
According to the question, cross-over effect in data can tend to eliminate the impact of regression artifact in which different treatment is received by subject in a series to cancel out regression.
Other options are incorrect because history, attrition or local history are not the factors that can be eliminated by crossover effect.Thus, the correct option is regression artifact.
