Stewart lost his lucky hat during the storm. He bought a new one yesterday.

Which is the best way to combine these two sentences?
A.
Since Stewart lost his lucky hat during the storm and bought a new one yesterday.
B.
Stewart lost his lucky hat during the storm, so he bought a new one yesterday.
C.
Stewart lost his lucky hat during the storm he bought a new one yesterday.
D.
Stewart lost his lucky hat during the storm bought a new one yesterday.