Import-VApp Question

Import-VApp requires a VMHost as a parameter. But when I import an OVA file manually on vSphere I can pick a resource pool.

How does vSphere determine what host to pick when going through the GUI (clicking a resource pool), and how can I replicate that with Import-VApp?

I hope that makes sense, let me know if I can further clarify. I'm still learning all the VMware architecture and how it works.