How do you know that a Development Team is cross-functional? (choose the best answer)

How do you know that a Development Team is cross-functional? (choose the best answer)
A . There are no conflicts within the Development Team.
B. Development Team has all the skills to create a potentially releasable increment by the end of every Sprint.
C. A few of the Development Team members pair program and do Test Driven Development.
D. Every member of the Development Team is able to perform every task.

Answer: B