Your best friend, a personal trainer, convinces you to sign up for a free gym membership at the gym where they work. You think this is a great deal because you can use the gym 24 hours a day, so you sign up. Then after 2 weeks, you realize that the gym charges you $100 a month, $20 extra for each class that you take there, and you don't get personal training options. This is unfortunately an example of: 

a. bait-and-switch technique 

b. that's-not-all technique 

c. not-so-free sample technique 

d. low-ball technique