Disk encryption is a type of encryption that protects the entire contents of a hard drive or a removable storage device by using a secret key to scramble the data. Disk encryption would best protect a laptop computer in the event of theft because it would prevent unauthorized access to the data on the laptop. Email, VPN, and HTTPS are not types of encryption that protect the entire contents of a laptop computer. Reference: CompTIA IT Fundamentals+ Study Guide: Exam FC0-U61, Second Edition, Chapter 8: Security Concepts, page 308.