2.5 Simple random sample. I plan to take a sample of 10 students in my introductory statistics class. Which of the following is a simple random sample?

a. I choose the 10 students sitting in the front row. Students select seats at random, so this would be a simple random sample.

b. I choose the first 10 students who enter the classroom. Students arrive at random, so this would be a simple random sample.

c. I write the names of all the students on similar slips of paper, put the slips of paper in a box, mix them well, and draw 10 slips from the box. The 10 names drawn are my sample.

d. All of the above are simple random samples.