Lee Has Established a New Startup Where They Develop Android

Lee has established a new startup where they develop android applications. In order to meet memory requirements of the company, Lee has hired a Cloud Service Provider, who offered memory space along with virtual systems. Lee was dissatisfied with their service and wanted to move to another CSP, but was denied as a part of the contract, which reads that the user cannot switch to another CSP. What is this condition called?

A) Virtualization
B) Lock-in
C) Resource Isolation
D) Lock-up