What research method gathers information by asking questions to a sampling of people?

The test scores of 30 students are listed below. Which number could be the 30th percentile?

31 41 45 48 52 55 56 56 63 65 67 67 69 70 70 74 75 78 79 79 80 81 83 85 85 87 90 92 95 99 A) 90 B) 56 C) 67 D) 64

One column of a table in a relational database is called a(n) ____

a. attribute b. relation c. tuple d. element