A researcher was interested in tracking the number of birds that became totally coated with oil and needed to be rescued during the BP oil spill in the Gulf of Mexico in her research area. Everyday she would go out in her boat and rescue the birds that were coated. At the end of each day, she recorded the total number of birds that she rescued. What type of graph would she use to get an estimate of center and spread? O bar chart O scatterplot O dot plot O pie chart