In which sentence is the word shelter used as a predicate nominative?

AParents try to shelter their children from harm.
BA lean-to is a shelter that hikers use in the mountains.
CWe got our puppy from the local dog shelter.
DWe took shelter under an outcropping of rocks.

Which word in this sentence is a participle?

My sister is a young fashion designer but has a flourishing business.

Ayoung
Bfashion
Chas
Dflourishing