Measurement bias caused by observer expectations can be avoided by using observers.

Naive.

Explanation:

Naive observer may be defined as the observer that are unaware of the experimental condition or the study purpose of the experiment. They do not know the effect of the observation period during the experiment.

The data collected and obtained by the naive observer is not likely to be influenced by the observer. They do not influence the observer's expectation and can be avoided by the measurement observer.

Thus, the correct answer is naive.

this website is for anybody really not just for girls just saying, also while a lot of males are mean and you know there are the few who are kind and then there's the nice-guys but then theirs also guys like me who are shy we don't get out much because there are people like you who exist who would most likely punch a guy in the face so next time just think about things before you post them to a website where guys and girls can see your question.