题目选项分析

In social science research, "highest education level attained" would refer to the most advanced grade or degree achieved by an individual—for some individuals, it may be a grade in grade school, and for other individuals, it may be a Bachelor's Degree, a Master's Degree, or Ph.D. (which is considered the highest education level). A recent study has shown a strong correlation between highest education level attained and proficiency in chess. Another result, studied at many points throughout the 20th century, shows a marked positive correlation between highest education level attained and income level.

Assuming the statements above are true, what conclusion can be drawn?

【选项】It is possible that a person who has attained only a sixth grade level of education could earn more than a person who has a Ph. D.