Final Sample Size

Read the article attach and aswer the following

1. From the description in the Methods section, how were the participants chosen for inclusion into the study? What were the criteria for exclusion? What was the final sample size for this study? 

2. In the References, can you spot the citation “CDC, 2013”? What are the letters a, b, c for? Do you know if that’s also an APA formatting requirement (to use letters a, b, etc after the year)?