A Researcher Concludes That Stress Levels Are Higher Following a Major

A researcher concludes that stress levels are higher following a major versus a minor traffic accident (95% confidence interval [CI] 1.86-3.02) .If the null hypothesis stated that there would be no difference (null hypothesis: $\mu$ = 0) ,then what is the effect size for this confidence interval?

A) Between 1.86% and 3.02% of the variability in stress levels can be accounted for by type of traffic accident.
B) Ratings of stress shifted more than 1.86 points in the population.
C) Ratings of stress shifted between 1.86 and 3.02 points in the population.
D) There is not enough information to answer this question.