Please indicate the sampling design and data collection tool(s) used in the following studies.
a) A researcher wanted to investigate the prevalence of depression among type II diabetic patients and to examine the relationship between depression and socio-demographic factors, clinical factors, and glycemic control. He conducted a cross-sectional study at a primary healthcare center in Naples, Palestine. Two hundred and ninety-four patients were surveyed for the presence of depressive symptoms using Beck Depression Inventory (BDI-II) scale (a 21-question multiple-choice self-report inventory). Participants were recruited from the diabetic clinic while they were waiting to be seen by their health care providers. The inclusion criteria for this study were males and females 18 years old and older who reported to the researcher that they had type 2 diabetes