Layla is a salesperson at mandrin corp. and is preparing to make a sales call. she should use a check-back after she:

The answer to this question is Finishes a Feature-benefit sequence
Features-benefit sequence refers to marketing tactics that focused on making cosumers aware about the feature of our product and make them aware how that feature will benefit the consumers in their life. 
The check back in this context is used in order to find out if the potential consumers already developed their awareness upon those two things.