In which sentence is the singular possessive of tree formed correctly?
A.
I watched a trees branches sway in the wind.
B.
I watched a trees's branches sway in the wind.
C.
I watched a tree's branches sway in the wind.
D.
I watched a trees' branches sway in the wind.
A.
I watched a trees branches sway in the wind.
B.
I watched a trees's branches sway in the wind.
C.
I watched a tree's branches sway in the wind.
D.
I watched a trees' branches sway in the wind.