Context Birds of many species retain the same breeding partner year after year. In some species, male and female partners migrate separately and spend the winter in different places, often thousands of miles apart. A recent study recorded the spring arrival dates (measured as number of days since March 31st) of male and female bird-couples on the breeding grounds in the year after they were observed breeding together. Research aim The researchers hope to use the collected data as evidence that there is a linear association between the arrival dates of coupled male and female birds. The following multiple-choice options contain math elements, so you may need to read them in your screen reader's "reading" or "browse" mode instead of "forms" or "focus" mode. Choice 1 of 6: 1-sample z-test for a population proportion, p p Choice 2 of 6: a t-test for a population mean difference of paired observations, d d Choice 3 of 6: ANOVA Choice 4 of 6: 2-sample t-test for a difference in independent population means, 1 2 1 2 Choice 5 of 6: Simple linear regression Choice 6 of 6: 1-sample t-test for a population mean