Which of these is an example ofsystematic randomsample?

• a.)
• Picking out the telephone number of every 20th person from a directory.
• b.)
• Picking out 10 names from a group of 50 students.
• c.)
• Selecting one card from a deck of 52 well-shuffled cards.
• d.)
• Choosing 10 marbles from a jar containing 40 marbles.