Final answer:
Lindsey Stirling's potential collaboration with the Vitamin String Quartet to make them a quintet would depend on their musical preferences and goals.
Step-by-step explanation:
The Vitamin String Quartet is a classical string quartet known for their instrumental tribute versions of popular music. Lindsey Stirling, on the other hand, is a contemporary violinist known for her unique blend of classical, electronic, and rock music. While both are talented musicians, they have different styles and genres. If Lindsey Stirling were to join the Vitamin String Quartet, it would change the dynamics of the ensemble, potentially making them a quintet. However, this decision would depend on the musical preferences and goals of both Lindsey Stirling and the members of the Vitamin String Quartet.